JezK
Edit File: recfunctions.py
""" Collection of utilities to manipulate structured arrays. Most of these functions were initially implemented by John Hunter for matplotlib. They have been rewritten and extended for convenience. """ import itertools import numpy as np import numpy.ma as ma from numpy import ndarray, recarray from numpy.ma import MaskedArray from numpy.ma.mrecords import MaskedRecords from numpy.core.overrides import array_function_dispatch from numpy.lib._iotools import _is_string_like _check_fill_value = np.ma.core._check_fill_value __all__ = [ 'append_fields', 'apply_along_fields', 'assign_fields_by_name', 'drop_fields', 'find_duplicates', 'flatten_descr', 'get_fieldstructure', 'get_names', 'get_names_flat', 'join_by', 'merge_arrays', 'rec_append_fields', 'rec_drop_fields', 'rec_join', 'recursive_fill_fields', 'rename_fields', 'repack_fields', 'require_fields', 'stack_arrays', 'structured_to_unstructured', 'unstructured_to_structured', ] def _recursive_fill_fields_dispatcher(input, output): return (input, output) @array_function_dispatch(_recursive_fill_fields_dispatcher) def recursive_fill_fields(input, output): """ Fills fields from output with fields from input, with support for nested structures. Parameters ---------- input : ndarray Input array. output : ndarray Output array. Notes ----- * `output` should be at least the same size as `input` Examples -------- >>> from numpy.lib import recfunctions as rfn >>> a = np.array([(1, 10.), (2, 20.)], dtype=[('A', np.int64), ('B', np.float64)]) >>> b = np.zeros((3,), dtype=a.dtype) >>> rfn.recursive_fill_fields(a, b) array([(1, 10.), (2, 20.), (0, 0.)], dtype=[('A', '<i8'), ('B', '<f8')]) """ newdtype = output.dtype for field in newdtype.names: try: current = input[field] except ValueError: continue if current.dtype.names is not None: recursive_fill_fields(current, output[field]) else: output[field][:len(current)] = current return output def _get_fieldspec(dtype): """ Produce a list of name/dtype pairs corresponding to the dtype fields Similar to dtype.descr, but the second item of each tuple is a dtype, not a string. As a result, this handles subarray dtypes Can be passed to the dtype constructor to reconstruct the dtype, noting that this (deliberately) discards field offsets. Examples -------- >>> dt = np.dtype([(('a', 'A'), np.int64), ('b', np.double, 3)]) >>> dt.descr [(('a', 'A'), '<i8'), ('b', '<f8', (3,))] >>> _get_fieldspec(dt) [(('a', 'A'), dtype('int64')), ('b', dtype(('<f8', (3,))))] """ if dtype.names is None: # .descr returns a nameless field, so we should too return [('', dtype)] else: fields = ((name, dtype.fields[name]) for name in dtype.names) # keep any titles, if present return [ (name if len(f) == 2 else (f[2], name), f[0]) for name, f in fields ] def get_names(adtype): """ Returns the field names of the input datatype as a tuple. Input datatype must have fields otherwise error is raised. Parameters ---------- adtype : dtype Input datatype Examples -------- >>> from numpy.lib import recfunctions as rfn >>> rfn.get_names(np.empty((1,), dtype=[('A', int)]).dtype) ('A',) >>> rfn.get_names(np.empty((1,), dtype=[('A',int), ('B', float)]).dtype) ('A', 'B') >>> adtype = np.dtype([('a', int), ('b', [('ba', int), ('bb', int)])]) >>> rfn.get_names(adtype) ('a', ('b', ('ba', 'bb'))) """ listnames = [] names = adtype.names for name in names: current = adtype[name] if current.names is not None: listnames.append((name, tuple(get_names(current)))) else: listnames.append(name) return tuple(listnames) def get_names_flat(adtype): """ Returns the field names of the input datatype as a tuple. Input datatype must have fields otherwise error is raised. Nested structure are flattened beforehand. Parameters ---------- adtype : dtype Input datatype Examples -------- >>> from numpy.lib import recfunctions as rfn >>> rfn.get_names_flat(np.empty((1,), dtype=[('A', int)]).dtype) is None False >>> rfn.get_names_flat(np.empty((1,), dtype=[('A',int), ('B', str)]).dtype) ('A', 'B') >>> adtype = np.dtype([('a', int), ('b', [('ba', int), ('bb', int)])]) >>> rfn.get_names_flat(adtype) ('a', 'b', 'ba', 'bb') """ listnames = [] names = adtype.names for name in names: listnames.append(name) current = adtype[name] if current.names is not None: listnames.extend(get_names_flat(current)) return tuple(listnames) def flatten_descr(ndtype): """ Flatten a structured data-type description. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> ndtype = np.dtype([('a', '<i4'), ('b', [('ba', '<f8'), ('bb', '<i4')])]) >>> rfn.flatten_descr(ndtype) (('a', dtype('int32')), ('ba', dtype('float64')), ('bb', dtype('int32'))) """ names = ndtype.names if names is None: return (('', ndtype),) else: descr = [] for field in names: (typ, _) = ndtype.fields[field] if typ.names is not None: descr.extend(flatten_descr(typ)) else: descr.append((field, typ)) return tuple(descr) def _zip_dtype(seqarrays, flatten=False): newdtype = [] if flatten: for a in seqarrays: newdtype.extend(flatten_descr(a.dtype)) else: for a in seqarrays: current = a.dtype if current.names is not None and len(current.names) == 1: # special case - dtypes of 1 field are flattened newdtype.extend(_get_fieldspec(current)) else: newdtype.append(('', current)) return np.dtype(newdtype) def _zip_descr(seqarrays, flatten=False): """ Combine the dtype description of a series of arrays. Parameters ---------- seqarrays : sequence of arrays Sequence of arrays flatten : {boolean}, optional Whether to collapse nested descriptions. """ return _zip_dtype(seqarrays, flatten=flatten).descr def get_fieldstructure(adtype, lastname=None, parents=None,): """ Returns a dictionary with fields indexing lists of their parent fields. This function is used to simplify access to fields nested in other fields. Parameters ---------- adtype : np.dtype Input datatype lastname : optional Last processed field name (used internally during recursion). parents : dictionary Dictionary of parent fields (used interbally during recursion). Examples -------- >>> from numpy.lib import recfunctions as rfn >>> ndtype = np.dtype([('A', int), ... ('B', [('BA', int), ... ('BB', [('BBA', int), ('BBB', int)])])]) >>> rfn.get_fieldstructure(ndtype) ... # XXX: possible regression, order of BBA and BBB is swapped {'A': [], 'B': [], 'BA': ['B'], 'BB': ['B'], 'BBA': ['B', 'BB'], 'BBB': ['B', 'BB']} """ if parents is None: parents = {} names = adtype.names for name in names: current = adtype[name] if current.names is not None: if lastname: parents[name] = [lastname, ] else: parents[name] = [] parents.update(get_fieldstructure(current, name, parents)) else: lastparent = [_ for _ in (parents.get(lastname, []) or [])] if lastparent: lastparent.append(lastname) elif lastname: lastparent = [lastname, ] parents[name] = lastparent or [] return parents def _izip_fields_flat(iterable): """ Returns an iterator of concatenated fields from a sequence of arrays, collapsing any nested structure. """ for element in iterable: if isinstance(element, np.void): yield from _izip_fields_flat(tuple(element)) else: yield element def _izip_fields(iterable): """ Returns an iterator of concatenated fields from a sequence of arrays. """ for element in iterable: if (hasattr(element, '__iter__') and not isinstance(element, str)): yield from _izip_fields(element) elif isinstance(element, np.void) and len(tuple(element)) == 1: # this statement is the same from the previous expression yield from _izip_fields(element) else: yield element def _izip_records(seqarrays, fill_value=None, flatten=True): """ Returns an iterator of concatenated items from a sequence of arrays. Parameters ---------- seqarrays : sequence of arrays Sequence of arrays. fill_value : {None, integer} Value used to pad shorter iterables. flatten : {True, False}, Whether to """ # Should we flatten the items, or just use a nested approach if flatten: zipfunc = _izip_fields_flat else: zipfunc = _izip_fields for tup in itertools.zip_longest(*seqarrays, fillvalue=fill_value): yield tuple(zipfunc(tup)) def _fix_output(output, usemask=True, asrecarray=False): """ Private function: return a recarray, a ndarray, a MaskedArray or a MaskedRecords depending on the input parameters """ if not isinstance(output, MaskedArray): usemask = False if usemask: if asrecarray: output = output.view(MaskedRecords) else: output = ma.filled(output) if asrecarray: output = output.view(recarray) return output def _fix_defaults(output, defaults=None): """ Update the fill_value and masked data of `output` from the default given in a dictionary defaults. """ names = output.dtype.names (data, mask, fill_value) = (output.data, output.mask, output.fill_value) for (k, v) in (defaults or {}).items(): if k in names: fill_value[k] = v data[k][mask[k]] = v return output def _merge_arrays_dispatcher(seqarrays, fill_value=None, flatten=None, usemask=None, asrecarray=None): return seqarrays @array_function_dispatch(_merge_arrays_dispatcher) def merge_arrays(seqarrays, fill_value=-1, flatten=False, usemask=False, asrecarray=False): """ Merge arrays field by field. Parameters ---------- seqarrays : sequence of ndarrays Sequence of arrays fill_value : {float}, optional Filling value used to pad missing data on the shorter arrays. flatten : {False, True}, optional Whether to collapse nested fields. usemask : {False, True}, optional Whether to return a masked array or not. asrecarray : {False, True}, optional Whether to return a recarray (MaskedRecords) or not. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> rfn.merge_arrays((np.array([1, 2]), np.array([10., 20., 30.]))) array([( 1, 10.), ( 2, 20.), (-1, 30.)], dtype=[('f0', '<i8'), ('f1', '<f8')]) >>> rfn.merge_arrays((np.array([1, 2], dtype=np.int64), ... np.array([10., 20., 30.])), usemask=False) array([(1, 10.0), (2, 20.0), (-1, 30.0)], dtype=[('f0', '<i8'), ('f1', '<f8')]) >>> rfn.merge_arrays((np.array([1, 2]).view([('a', np.int64)]), ... np.array([10., 20., 30.])), ... usemask=False, asrecarray=True) rec.array([( 1, 10.), ( 2, 20.), (-1, 30.)], dtype=[('a', '<i8'), ('f1', '<f8')]) Notes ----- * Without a mask, the missing value will be filled with something, depending on what its corresponding type: * ``-1`` for integers * ``-1.0`` for floating point numbers * ``'-'`` for characters * ``'-1'`` for strings * ``True`` for boolean values * XXX: I just obtained these values empirically """ # Only one item in the input sequence ? if (len(seqarrays) == 1): seqarrays = np.asanyarray(seqarrays[0]) # Do we have a single ndarray as input ? if isinstance(seqarrays, (ndarray, np.void)): seqdtype = seqarrays.dtype # Make sure we have named fields if seqdtype.names is None: seqdtype = np.dtype([('', seqdtype)]) if not flatten or _zip_dtype((seqarrays,), flatten=True) == seqdtype: # Minimal processing needed: just make sure everything's a-ok seqarrays = seqarrays.ravel() # Find what type of array we must return if usemask: if asrecarray: seqtype = MaskedRecords else: seqtype = MaskedArray elif asrecarray: seqtype = recarray else: seqtype = ndarray return seqarrays.view(dtype=seqdtype, type=seqtype) else: seqarrays = (seqarrays,) else: # Make sure we have arrays in the input sequence seqarrays = [np.asanyarray(_m) for _m in seqarrays] # Find the sizes of the inputs and their maximum sizes = tuple(a.size for a in seqarrays) maxlength = max(sizes) # Get the dtype of the output (flattening if needed) newdtype = _zip_dtype(seqarrays, flatten=flatten) # Initialize the sequences for data and mask seqdata = [] seqmask = [] # If we expect some kind of MaskedArray, make a special loop. if usemask: for (a, n) in zip(seqarrays, sizes): nbmissing = (maxlength - n) # Get the data and mask data = a.ravel().__array__() mask = ma.getmaskarray(a).ravel() # Get the filling value (if needed) if nbmissing: fval = _check_fill_value(fill_value, a.dtype) if isinstance(fval, (ndarray, np.void)): if len(fval.dtype) == 1: fval = fval.item()[0] fmsk = True else: fval = np.array(fval, dtype=a.dtype, ndmin=1) fmsk = np.ones((1,), dtype=mask.dtype) else: fval = None fmsk = True # Store an iterator padding the input to the expected length seqdata.append(itertools.chain(data, [fval] * nbmissing)) seqmask.append(itertools.chain(mask, [fmsk] * nbmissing)) # Create an iterator for the data data = tuple(_izip_records(seqdata, flatten=flatten)) output = ma.array(np.fromiter(data, dtype=newdtype, count=maxlength), mask=list(_izip_records(seqmask, flatten=flatten))) if asrecarray: output = output.view(MaskedRecords) else: # Same as before, without the mask we don't need... for (a, n) in zip(seqarrays, sizes): nbmissing = (maxlength - n) data = a.ravel().__array__() if nbmissing: fval = _check_fill_value(fill_value, a.dtype) if isinstance(fval, (ndarray, np.void)): if len(fval.dtype) == 1: fval = fval.item()[0] else: fval = np.array(fval, dtype=a.dtype, ndmin=1) else: fval = None seqdata.append(itertools.chain(data, [fval] * nbmissing)) output = np.fromiter(tuple(_izip_records(seqdata, flatten=flatten)), dtype=newdtype, count=maxlength) if asrecarray: output = output.view(recarray) # And we're done... return output def _drop_fields_dispatcher(base, drop_names, usemask=None, asrecarray=None): return (base,) @array_function_dispatch(_drop_fields_dispatcher) def drop_fields(base, drop_names, usemask=True, asrecarray=False): """ Return a new array with fields in `drop_names` dropped. Nested fields are supported. .. versionchanged:: 1.18.0 `drop_fields` returns an array with 0 fields if all fields are dropped, rather than returning ``None`` as it did previously. Parameters ---------- base : array Input array drop_names : string or sequence String or sequence of strings corresponding to the names of the fields to drop. usemask : {False, True}, optional Whether to return a masked array or not. asrecarray : string or sequence, optional Whether to return a recarray or a mrecarray (`asrecarray=True`) or a plain ndarray or masked array with flexible dtype. The default is False. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> a = np.array([(1, (2, 3.0)), (4, (5, 6.0))], ... dtype=[('a', np.int64), ('b', [('ba', np.double), ('bb', np.int64)])]) >>> rfn.drop_fields(a, 'a') array([((2., 3),), ((5., 6),)], dtype=[('b', [('ba', '<f8'), ('bb', '<i8')])]) >>> rfn.drop_fields(a, 'ba') array([(1, (3,)), (4, (6,))], dtype=[('a', '<i8'), ('b', [('bb', '<i8')])]) >>> rfn.drop_fields(a, ['ba', 'bb']) array([(1,), (4,)], dtype=[('a', '<i8')]) """ if _is_string_like(drop_names): drop_names = [drop_names] else: drop_names = set(drop_names) def _drop_descr(ndtype, drop_names): names = ndtype.names newdtype = [] for name in names: current = ndtype[name] if name in drop_names: continue if current.names is not None: descr = _drop_descr(current, drop_names) if descr: newdtype.append((name, descr)) else: newdtype.append((name, current)) return newdtype newdtype = _drop_descr(base.dtype, drop_names) output = np.empty(base.shape, dtype=newdtype) output = recursive_fill_fields(base, output) return _fix_output(output, usemask=usemask, asrecarray=asrecarray) def _keep_fields(base, keep_names, usemask=True, asrecarray=False): """ Return a new array keeping only the fields in `keep_names`, and preserving the order of those fields. Parameters ---------- base : array Input array keep_names : string or sequence String or sequence of strings corresponding to the names of the fields to keep. Order of the names will be preserved. usemask : {False, True}, optional Whether to return a masked array or not. asrecarray : string or sequence, optional Whether to return a recarray or a mrecarray (`asrecarray=True`) or a plain ndarray or masked array with flexible dtype. The default is False. """ newdtype = [(n, base.dtype[n]) for n in keep_names] output = np.empty(base.shape, dtype=newdtype) output = recursive_fill_fields(base, output) return _fix_output(output, usemask=usemask, asrecarray=asrecarray) def _rec_drop_fields_dispatcher(base, drop_names): return (base,) @array_function_dispatch(_rec_drop_fields_dispatcher) def rec_drop_fields(base, drop_names): """ Returns a new numpy.recarray with fields in `drop_names` dropped. """ return drop_fields(base, drop_names, usemask=False, asrecarray=True) def _rename_fields_dispatcher(base, namemapper): return (base,) @array_function_dispatch(_rename_fields_dispatcher) def rename_fields(base, namemapper): """ Rename the fields from a flexible-datatype ndarray or recarray. Nested fields are supported. Parameters ---------- base : ndarray Input array whose fields must be modified. namemapper : dictionary Dictionary mapping old field names to their new version. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> a = np.array([(1, (2, [3.0, 30.])), (4, (5, [6.0, 60.]))], ... dtype=[('a', int),('b', [('ba', float), ('bb', (float, 2))])]) >>> rfn.rename_fields(a, {'a':'A', 'bb':'BB'}) array([(1, (2., [ 3., 30.])), (4, (5., [ 6., 60.]))], dtype=[('A', '<i8'), ('b', [('ba', '<f8'), ('BB', '<f8', (2,))])]) """ def _recursive_rename_fields(ndtype, namemapper): newdtype = [] for name in ndtype.names: newname = namemapper.get(name, name) current = ndtype[name] if current.names is not None: newdtype.append( (newname, _recursive_rename_fields(current, namemapper)) ) else: newdtype.append((newname, current)) return newdtype newdtype = _recursive_rename_fields(base.dtype, namemapper) return base.view(newdtype) def _append_fields_dispatcher(base, names, data, dtypes=None, fill_value=None, usemask=None, asrecarray=None): yield base yield from data @array_function_dispatch(_append_fields_dispatcher) def append_fields(base, names, data, dtypes=None, fill_value=-1, usemask=True, asrecarray=False): """ Add new fields to an existing array. The names of the fields are given with the `names` arguments, the corresponding values with the `data` arguments. If a single field is appended, `names`, `data` and `dtypes` do not have to be lists but just values. Parameters ---------- base : array Input array to extend. names : string, sequence String or sequence of strings corresponding to the names of the new fields. data : array or sequence of arrays Array or sequence of arrays storing the fields to add to the base. dtypes : sequence of datatypes, optional Datatype or sequence of datatypes. If None, the datatypes are estimated from the `data`. fill_value : {float}, optional Filling value used to pad missing data on the shorter arrays. usemask : {False, True}, optional Whether to return a masked array or not. asrecarray : {False, True}, optional Whether to return a recarray (MaskedRecords) or not. """ # Check the names if isinstance(names, (tuple, list)): if len(names) != len(data): msg = "The number of arrays does not match the number of names" raise ValueError(msg) elif isinstance(names, str): names = [names, ] data = [data, ] # if dtypes is None: data = [np.array(a, copy=False, subok=True) for a in data] data = [a.view([(name, a.dtype)]) for (name, a) in zip(names, data)] else: if not isinstance(dtypes, (tuple, list)): dtypes = [dtypes, ] if len(data) != len(dtypes): if len(dtypes) == 1: dtypes = dtypes * len(data) else: msg = "The dtypes argument must be None, a dtype, or a list." raise ValueError(msg) data = [np.array(a, copy=False, subok=True, dtype=d).view([(n, d)]) for (a, n, d) in zip(data, names, dtypes)] # base = merge_arrays(base, usemask=usemask, fill_value=fill_value) if len(data) > 1: data = merge_arrays(data, flatten=True, usemask=usemask, fill_value=fill_value) else: data = data.pop() # output = ma.masked_all( max(len(base), len(data)), dtype=_get_fieldspec(base.dtype) + _get_fieldspec(data.dtype)) output = recursive_fill_fields(base, output) output = recursive_fill_fields(data, output) # return _fix_output(output, usemask=usemask, asrecarray=asrecarray) def _rec_append_fields_dispatcher(base, names, data, dtypes=None): yield base yield from data @array_function_dispatch(_rec_append_fields_dispatcher) def rec_append_fields(base, names, data, dtypes=None): """ Add new fields to an existing array. The names of the fields are given with the `names` arguments, the corresponding values with the `data` arguments. If a single field is appended, `names`, `data` and `dtypes` do not have to be lists but just values. Parameters ---------- base : array Input array to extend. names : string, sequence String or sequence of strings corresponding to the names of the new fields. data : array or sequence of arrays Array or sequence of arrays storing the fields to add to the base. dtypes : sequence of datatypes, optional Datatype or sequence of datatypes. If None, the datatypes are estimated from the `data`. See Also -------- append_fields Returns ------- appended_array : np.recarray """ return append_fields(base, names, data=data, dtypes=dtypes, asrecarray=True, usemask=False) def _repack_fields_dispatcher(a, align=None, recurse=None): return (a,) @array_function_dispatch(_repack_fields_dispatcher) def repack_fields(a, align=False, recurse=False): """ Re-pack the fields of a structured array or dtype in memory. The memory layout of structured datatypes allows fields at arbitrary byte offsets. This means the fields can be separated by padding bytes, their offsets can be non-monotonically increasing, and they can overlap. This method removes any overlaps and reorders the fields in memory so they have increasing byte offsets, and adds or removes padding bytes depending on the `align` option, which behaves like the `align` option to `numpy.dtype`. If `align=False`, this method produces a "packed" memory layout in which each field starts at the byte the previous field ended, and any padding bytes are removed. If `align=True`, this methods produces an "aligned" memory layout in which each field's offset is a multiple of its alignment, and the total itemsize is a multiple of the largest alignment, by adding padding bytes as needed. Parameters ---------- a : ndarray or dtype array or dtype for which to repack the fields. align : boolean If true, use an "aligned" memory layout, otherwise use a "packed" layout. recurse : boolean If True, also repack nested structures. Returns ------- repacked : ndarray or dtype Copy of `a` with fields repacked, or `a` itself if no repacking was needed. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> def print_offsets(d): ... print("offsets:", [d.fields[name][1] for name in d.names]) ... print("itemsize:", d.itemsize) ... >>> dt = np.dtype('u1, <i8, <f8', align=True) >>> dt dtype({'names': ['f0', 'f1', 'f2'], 'formats': ['u1', '<i8', '<f8'], \ 'offsets': [0, 8, 16], 'itemsize': 24}, align=True) >>> print_offsets(dt) offsets: [0, 8, 16] itemsize: 24 >>> packed_dt = rfn.repack_fields(dt) >>> packed_dt dtype([('f0', 'u1'), ('f1', '<i8'), ('f2', '<f8')]) >>> print_offsets(packed_dt) offsets: [0, 1, 9] itemsize: 17 """ if not isinstance(a, np.dtype): dt = repack_fields(a.dtype, align=align, recurse=recurse) return a.astype(dt, copy=False) if a.names is None: return a fieldinfo = [] for name in a.names: tup = a.fields[name] if recurse: fmt = repack_fields(tup[0], align=align, recurse=True) else: fmt = tup[0] if len(tup) == 3: name = (tup[2], name) fieldinfo.append((name, fmt)) dt = np.dtype(fieldinfo, align=align) return np.dtype((a.type, dt)) def _get_fields_and_offsets(dt, offset=0): """ Returns a flat list of (dtype, count, offset) tuples of all the scalar fields in the dtype "dt", including nested fields, in left to right order. """ # counts up elements in subarrays, including nested subarrays, and returns # base dtype and count def count_elem(dt): count = 1 while dt.shape != (): for size in dt.shape: count *= size dt = dt.base return dt, count fields = [] for name in dt.names: field = dt.fields[name] f_dt, f_offset = field[0], field[1] f_dt, n = count_elem(f_dt) if f_dt.names is None: fields.append((np.dtype((f_dt, (n,))), n, f_offset + offset)) else: subfields = _get_fields_and_offsets(f_dt, f_offset + offset) size = f_dt.itemsize for i in range(n): if i == 0: # optimization: avoid list comprehension if no subarray fields.extend(subfields) else: fields.extend([(d, c, o + i*size) for d, c, o in subfields]) return fields def _structured_to_unstructured_dispatcher(arr, dtype=None, copy=None, casting=None): return (arr,) @array_function_dispatch(_structured_to_unstructured_dispatcher) def structured_to_unstructured(arr, dtype=None, copy=False, casting='unsafe'): """ Converts an n-D structured array into an (n+1)-D unstructured array. The new array will have a new last dimension equal in size to the number of field-elements of the input array. If not supplied, the output datatype is determined from the numpy type promotion rules applied to all the field datatypes. Nested fields, as well as each element of any subarray fields, all count as a single field-elements. Parameters ---------- arr : ndarray Structured array or dtype to convert. Cannot contain object datatype. dtype : dtype, optional The dtype of the output unstructured array. copy : bool, optional See copy argument to `numpy.ndarray.astype`. If true, always return a copy. If false, and `dtype` requirements are satisfied, a view is returned. casting : {'no', 'equiv', 'safe', 'same_kind', 'unsafe'}, optional See casting argument of `numpy.ndarray.astype`. Controls what kind of data casting may occur. Returns ------- unstructured : ndarray Unstructured array with one more dimension. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> a = np.zeros(4, dtype=[('a', 'i4'), ('b', 'f4,u2'), ('c', 'f4', 2)]) >>> a array([(0, (0., 0), [0., 0.]), (0, (0., 0), [0., 0.]), (0, (0., 0), [0., 0.]), (0, (0., 0), [0., 0.])], dtype=[('a', '<i4'), ('b', [('f0', '<f4'), ('f1', '<u2')]), ('c', '<f4', (2,))]) >>> rfn.structured_to_unstructured(a) array([[0., 0., 0., 0., 0.], [0., 0., 0., 0., 0.], [0., 0., 0., 0., 0.], [0., 0., 0., 0., 0.]]) >>> b = np.array([(1, 2, 5), (4, 5, 7), (7, 8 ,11), (10, 11, 12)], ... dtype=[('x', 'i4'), ('y', 'f4'), ('z', 'f8')]) >>> np.mean(rfn.structured_to_unstructured(b[['x', 'z']]), axis=-1) array([ 3. , 5.5, 9. , 11. ]) """ if arr.dtype.names is None: raise ValueError('arr must be a structured array') fields = _get_fields_and_offsets(arr.dtype) n_fields = len(fields) if n_fields == 0 and dtype is None: raise ValueError("arr has no fields. Unable to guess dtype") elif n_fields == 0: # too many bugs elsewhere for this to work now raise NotImplementedError("arr with no fields is not supported") dts, counts, offsets = zip(*fields) names = ['f{}'.format(n) for n in range(n_fields)] if dtype is None: out_dtype = np.result_type(*[dt.base for dt in dts]) else: out_dtype = dtype # Use a series of views and casts to convert to an unstructured array: # first view using flattened fields (doesn't work for object arrays) # Note: dts may include a shape for subarrays flattened_fields = np.dtype({'names': names, 'formats': dts, 'offsets': offsets, 'itemsize': arr.dtype.itemsize}) arr = arr.view(flattened_fields) # next cast to a packed format with all fields converted to new dtype packed_fields = np.dtype({'names': names, 'formats': [(out_dtype, dt.shape) for dt in dts]}) arr = arr.astype(packed_fields, copy=copy, casting=casting) # finally is it safe to view the packed fields as the unstructured type return arr.view((out_dtype, (sum(counts),))) def _unstructured_to_structured_dispatcher(arr, dtype=None, names=None, align=None, copy=None, casting=None): return (arr,) @array_function_dispatch(_unstructured_to_structured_dispatcher) def unstructured_to_structured(arr, dtype=None, names=None, align=False, copy=False, casting='unsafe'): """ Converts an n-D unstructured array into an (n-1)-D structured array. The last dimension of the input array is converted into a structure, with number of field-elements equal to the size of the last dimension of the input array. By default all output fields have the input array's dtype, but an output structured dtype with an equal number of fields-elements can be supplied instead. Nested fields, as well as each element of any subarray fields, all count towards the number of field-elements. Parameters ---------- arr : ndarray Unstructured array or dtype to convert. dtype : dtype, optional The structured dtype of the output array names : list of strings, optional If dtype is not supplied, this specifies the field names for the output dtype, in order. The field dtypes will be the same as the input array. align : boolean, optional Whether to create an aligned memory layout. copy : bool, optional See copy argument to `numpy.ndarray.astype`. If true, always return a copy. If false, and `dtype` requirements are satisfied, a view is returned. casting : {'no', 'equiv', 'safe', 'same_kind', 'unsafe'}, optional See casting argument of `numpy.ndarray.astype`. Controls what kind of data casting may occur. Returns ------- structured : ndarray Structured array with fewer dimensions. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> dt = np.dtype([('a', 'i4'), ('b', 'f4,u2'), ('c', 'f4', 2)]) >>> a = np.arange(20).reshape((4,5)) >>> a array([[ 0, 1, 2, 3, 4], [ 5, 6, 7, 8, 9], [10, 11, 12, 13, 14], [15, 16, 17, 18, 19]]) >>> rfn.unstructured_to_structured(a, dt) array([( 0, ( 1., 2), [ 3., 4.]), ( 5, ( 6., 7), [ 8., 9.]), (10, (11., 12), [13., 14.]), (15, (16., 17), [18., 19.])], dtype=[('a', '<i4'), ('b', [('f0', '<f4'), ('f1', '<u2')]), ('c', '<f4', (2,))]) """ if arr.shape == (): raise ValueError('arr must have at least one dimension') n_elem = arr.shape[-1] if n_elem == 0: # too many bugs elsewhere for this to work now raise NotImplementedError("last axis with size 0 is not supported") if dtype is None: if names is None: names = ['f{}'.format(n) for n in range(n_elem)] out_dtype = np.dtype([(n, arr.dtype) for n in names], align=align) fields = _get_fields_and_offsets(out_dtype) dts, counts, offsets = zip(*fields) else: if names is not None: raise ValueError("don't supply both dtype and names") # if dtype is the args of np.dtype, construct it dtype = np.dtype(dtype) # sanity check of the input dtype fields = _get_fields_and_offsets(dtype) if len(fields) == 0: dts, counts, offsets = [], [], [] else: dts, counts, offsets = zip(*fields) if n_elem != sum(counts): raise ValueError('The length of the last dimension of arr must ' 'be equal to the number of fields in dtype') out_dtype = dtype if align and not out_dtype.isalignedstruct: raise ValueError("align was True but dtype is not aligned") names = ['f{}'.format(n) for n in range(len(fields))] # Use a series of views and casts to convert to a structured array: # first view as a packed structured array of one dtype packed_fields = np.dtype({'names': names, 'formats': [(arr.dtype, dt.shape) for dt in dts]}) arr = np.ascontiguousarray(arr).view(packed_fields) # next cast to an unpacked but flattened format with varied dtypes flattened_fields = np.dtype({'names': names, 'formats': dts, 'offsets': offsets, 'itemsize': out_dtype.itemsize}) arr = arr.astype(flattened_fields, copy=copy, casting=casting) # finally view as the final nested dtype and remove the last axis return arr.view(out_dtype)[..., 0] def _apply_along_fields_dispatcher(func, arr): return (arr,) @array_function_dispatch(_apply_along_fields_dispatcher) def apply_along_fields(func, arr): """ Apply function 'func' as a reduction across fields of a structured array. This is similar to `apply_along_axis`, but treats the fields of a structured array as an extra axis. The fields are all first cast to a common type following the type-promotion rules from `numpy.result_type` applied to the field's dtypes. Parameters ---------- func : function Function to apply on the "field" dimension. This function must support an `axis` argument, like np.mean, np.sum, etc. arr : ndarray Structured array for which to apply func. Returns ------- out : ndarray Result of the recution operation Examples -------- >>> from numpy.lib import recfunctions as rfn >>> b = np.array([(1, 2, 5), (4, 5, 7), (7, 8 ,11), (10, 11, 12)], ... dtype=[('x', 'i4'), ('y', 'f4'), ('z', 'f8')]) >>> rfn.apply_along_fields(np.mean, b) array([ 2.66666667, 5.33333333, 8.66666667, 11. ]) >>> rfn.apply_along_fields(np.mean, b[['x', 'z']]) array([ 3. , 5.5, 9. , 11. ]) """ if arr.dtype.names is None: raise ValueError('arr must be a structured array') uarr = structured_to_unstructured(arr) return func(uarr, axis=-1) # works and avoids axis requirement, but very, very slow: #return np.apply_along_axis(func, -1, uarr) def _assign_fields_by_name_dispatcher(dst, src, zero_unassigned=None): return dst, src @array_function_dispatch(_assign_fields_by_name_dispatcher) def assign_fields_by_name(dst, src, zero_unassigned=True): """ Assigns values from one structured array to another by field name. Normally in numpy >= 1.14, assignment of one structured array to another copies fields "by position", meaning that the first field from the src is copied to the first field of the dst, and so on, regardless of field name. This function instead copies "by field name", such that fields in the dst are assigned from the identically named field in the src. This applies recursively for nested structures. This is how structure assignment worked in numpy >= 1.6 to <= 1.13. Parameters ---------- dst : ndarray src : ndarray The source and destination arrays during assignment. zero_unassigned : bool, optional If True, fields in the dst for which there was no matching field in the src are filled with the value 0 (zero). This was the behavior of numpy <= 1.13. If False, those fields are not modified. """ if dst.dtype.names is None: dst[...] = src return for name in dst.dtype.names: if name not in src.dtype.names: if zero_unassigned: dst[name] = 0 else: assign_fields_by_name(dst[name], src[name], zero_unassigned) def _require_fields_dispatcher(array, required_dtype): return (array,) @array_function_dispatch(_require_fields_dispatcher) def require_fields(array, required_dtype): """ Casts a structured array to a new dtype using assignment by field-name. This function assigns from the old to the new array by name, so the value of a field in the output array is the value of the field with the same name in the source array. This has the effect of creating a new ndarray containing only the fields "required" by the required_dtype. If a field name in the required_dtype does not exist in the input array, that field is created and set to 0 in the output array. Parameters ---------- a : ndarray array to cast required_dtype : dtype datatype for output array Returns ------- out : ndarray array with the new dtype, with field values copied from the fields in the input array with the same name Examples -------- >>> from numpy.lib import recfunctions as rfn >>> a = np.ones(4, dtype=[('a', 'i4'), ('b', 'f8'), ('c', 'u1')]) >>> rfn.require_fields(a, [('b', 'f4'), ('c', 'u1')]) array([(1., 1), (1., 1), (1., 1), (1., 1)], dtype=[('b', '<f4'), ('c', 'u1')]) >>> rfn.require_fields(a, [('b', 'f4'), ('newf', 'u1')]) array([(1., 0), (1., 0), (1., 0), (1., 0)], dtype=[('b', '<f4'), ('newf', 'u1')]) """ out = np.empty(array.shape, dtype=required_dtype) assign_fields_by_name(out, array) return out def _stack_arrays_dispatcher(arrays, defaults=None, usemask=None, asrecarray=None, autoconvert=None): return arrays @array_function_dispatch(_stack_arrays_dispatcher) def stack_arrays(arrays, defaults=None, usemask=True, asrecarray=False, autoconvert=False): """ Superposes arrays fields by fields Parameters ---------- arrays : array or sequence Sequence of input arrays. defaults : dictionary, optional Dictionary mapping field names to the corresponding default values. usemask : {True, False}, optional Whether to return a MaskedArray (or MaskedRecords is `asrecarray==True`) or a ndarray. asrecarray : {False, True}, optional Whether to return a recarray (or MaskedRecords if `usemask==True`) or just a flexible-type ndarray. autoconvert : {False, True}, optional Whether automatically cast the type of the field to the maximum. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> x = np.array([1, 2,]) >>> rfn.stack_arrays(x) is x True >>> z = np.array([('A', 1), ('B', 2)], dtype=[('A', '|S3'), ('B', float)]) >>> zz = np.array([('a', 10., 100.), ('b', 20., 200.), ('c', 30., 300.)], ... dtype=[('A', '|S3'), ('B', np.double), ('C', np.double)]) >>> test = rfn.stack_arrays((z,zz)) >>> test masked_array(data=[(b'A', 1.0, --), (b'B', 2.0, --), (b'a', 10.0, 100.0), (b'b', 20.0, 200.0), (b'c', 30.0, 300.0)], mask=[(False, False, True), (False, False, True), (False, False, False), (False, False, False), (False, False, False)], fill_value=(b'N/A', 1.e+20, 1.e+20), dtype=[('A', 'S3'), ('B', '<f8'), ('C', '<f8')]) """ if isinstance(arrays, ndarray): return arrays elif len(arrays) == 1: return arrays[0] seqarrays = [np.asanyarray(a).ravel() for a in arrays] nrecords = [len(a) for a in seqarrays] ndtype = [a.dtype for a in seqarrays] fldnames = [d.names for d in ndtype] # dtype_l = ndtype[0] newdescr = _get_fieldspec(dtype_l) names = [n for n, d in newdescr] for dtype_n in ndtype[1:]: for fname, fdtype in _get_fieldspec(dtype_n): if fname not in names: newdescr.append((fname, fdtype)) names.append(fname) else: nameidx = names.index(fname) _, cdtype = newdescr[nameidx] if autoconvert: newdescr[nameidx] = (fname, max(fdtype, cdtype)) elif fdtype != cdtype: raise TypeError("Incompatible type '%s' <> '%s'" % (cdtype, fdtype)) # Only one field: use concatenate if len(newdescr) == 1: output = ma.concatenate(seqarrays) else: # output = ma.masked_all((np.sum(nrecords),), newdescr) offset = np.cumsum(np.r_[0, nrecords]) seen = [] for (a, n, i, j) in zip(seqarrays, fldnames, offset[:-1], offset[1:]): names = a.dtype.names if names is None: output['f%i' % len(seen)][i:j] = a else: for name in n: output[name][i:j] = a[name] if name not in seen: seen.append(name) # return _fix_output(_fix_defaults(output, defaults), usemask=usemask, asrecarray=asrecarray) def _find_duplicates_dispatcher( a, key=None, ignoremask=None, return_index=None): return (a,) @array_function_dispatch(_find_duplicates_dispatcher) def find_duplicates(a, key=None, ignoremask=True, return_index=False): """ Find the duplicates in a structured array along a given key Parameters ---------- a : array-like Input array key : {string, None}, optional Name of the fields along which to check the duplicates. If None, the search is performed by records ignoremask : {True, False}, optional Whether masked data should be discarded or considered as duplicates. return_index : {False, True}, optional Whether to return the indices of the duplicated values. Examples -------- >>> from numpy.lib import recfunctions as rfn >>> ndtype = [('a', int)] >>> a = np.ma.array([1, 1, 1, 2, 2, 3, 3], ... mask=[0, 0, 1, 0, 0, 0, 1]).view(ndtype) >>> rfn.find_duplicates(a, ignoremask=True, return_index=True) (masked_array(data=[(1,), (1,), (2,), (2,)], mask=[(False,), (False,), (False,), (False,)], fill_value=(999999,), dtype=[('a', '<i8')]), array([0, 1, 3, 4])) """ a = np.asanyarray(a).ravel() # Get a dictionary of fields fields = get_fieldstructure(a.dtype) # Get the sorting data (by selecting the corresponding field) base = a if key: for f in fields[key]: base = base[f] base = base[key] # Get the sorting indices and the sorted data sortidx = base.argsort() sortedbase = base[sortidx] sorteddata = sortedbase.filled() # Compare the sorting data flag = (sorteddata[:-1] == sorteddata[1:]) # If masked data must be ignored, set the flag to false where needed if ignoremask: sortedmask = sortedbase.recordmask flag[sortedmask[1:]] = False flag = np.concatenate(([False], flag)) # We need to take the point on the left as well (else we're missing it) flag[:-1] = flag[:-1] + flag[1:] duplicates = a[sortidx][flag] if return_index: return (duplicates, sortidx[flag]) else: return duplicates def _join_by_dispatcher( key, r1, r2, jointype=None, r1postfix=None, r2postfix=None, defaults=None, usemask=None, asrecarray=None): return (r1, r2) @array_function_dispatch(_join_by_dispatcher) def join_by(key, r1, r2, jointype='inner', r1postfix='1', r2postfix='2', defaults=None, usemask=True, asrecarray=False): """ Join arrays `r1` and `r2` on key `key`. The key should be either a string or a sequence of string corresponding to the fields used to join the array. An exception is raised if the `key` field cannot be found in the two input arrays. Neither `r1` nor `r2` should have any duplicates along `key`: the presence of duplicates will make the output quite unreliable. Note that duplicates are not looked for by the algorithm. Parameters ---------- key : {string, sequence} A string or a sequence of strings corresponding to the fields used for comparison. r1, r2 : arrays Structured arrays. jointype : {'inner', 'outer', 'leftouter'}, optional If 'inner', returns the elements common to both r1 and r2. If 'outer', returns the common elements as well as the elements of r1 not in r2 and the elements of not in r2. If 'leftouter', returns the common elements and the elements of r1 not in r2. r1postfix : string, optional String appended to the names of the fields of r1 that are present in r2 but absent of the key. r2postfix : string, optional String appended to the names of the fields of r2 that are present in r1 but absent of the key. defaults : {dictionary}, optional Dictionary mapping field names to the corresponding default values. usemask : {True, False}, optional Whether to return a MaskedArray (or MaskedRecords is `asrecarray==True`) or a ndarray. asrecarray : {False, True}, optional Whether to return a recarray (or MaskedRecords if `usemask==True`) or just a flexible-type ndarray. Notes ----- * The output is sorted along the key. * A temporary array is formed by dropping the fields not in the key for the two arrays and concatenating the result. This array is then sorted, and the common entries selected. The output is constructed by filling the fields with the selected entries. Matching is not preserved if there are some duplicates... """ # Check jointype if jointype not in ('inner', 'outer', 'leftouter'): raise ValueError( "The 'jointype' argument should be in 'inner', " "'outer' or 'leftouter' (got '%s' instead)" % jointype ) # If we have a single key, put it in a tuple if isinstance(key, str): key = (key,) # Check the keys if len(set(key)) != len(key): dup = next(x for n,x in enumerate(key) if x in key[n+1:]) raise ValueError("duplicate join key %r" % dup) for name in key: if name not in r1.dtype.names: raise ValueError('r1 does not have key field %r' % name) if name not in r2.dtype.names: raise ValueError('r2 does not have key field %r' % name) # Make sure we work with ravelled arrays r1 = r1.ravel() r2 = r2.ravel() # Fixme: nb2 below is never used. Commenting out for pyflakes. # (nb1, nb2) = (len(r1), len(r2)) nb1 = len(r1) (r1names, r2names) = (r1.dtype.names, r2.dtype.names) # Check the names for collision collisions = (set(r1names) & set(r2names)) - set(key) if collisions and not (r1postfix or r2postfix): msg = "r1 and r2 contain common names, r1postfix and r2postfix " msg += "can't both be empty" raise ValueError(msg) # Make temporary arrays of just the keys # (use order of keys in `r1` for back-compatibility) key1 = [ n for n in r1names if n in key ] r1k = _keep_fields(r1, key1) r2k = _keep_fields(r2, key1) # Concatenate the two arrays for comparison aux = ma.concatenate((r1k, r2k)) idx_sort = aux.argsort(order=key) aux = aux[idx_sort] # # Get the common keys flag_in = ma.concatenate(([False], aux[1:] == aux[:-1])) flag_in[:-1] = flag_in[1:] + flag_in[:-1] idx_in = idx_sort[flag_in] idx_1 = idx_in[(idx_in < nb1)] idx_2 = idx_in[(idx_in >= nb1)] - nb1 (r1cmn, r2cmn) = (len(idx_1), len(idx_2)) if jointype == 'inner': (r1spc, r2spc) = (0, 0) elif jointype == 'outer': idx_out = idx_sort[~flag_in] idx_1 = np.concatenate((idx_1, idx_out[(idx_out < nb1)])) idx_2 = np.concatenate((idx_2, idx_out[(idx_out >= nb1)] - nb1)) (r1spc, r2spc) = (len(idx_1) - r1cmn, len(idx_2) - r2cmn) elif jointype == 'leftouter': idx_out = idx_sort[~flag_in] idx_1 = np.concatenate((idx_1, idx_out[(idx_out < nb1)])) (r1spc, r2spc) = (len(idx_1) - r1cmn, 0) # Select the entries from each input (s1, s2) = (r1[idx_1], r2[idx_2]) # # Build the new description of the output array ....... # Start with the key fields ndtype = _get_fieldspec(r1k.dtype) # Add the fields from r1 for fname, fdtype in _get_fieldspec(r1.dtype): if fname not in key: ndtype.append((fname, fdtype)) # Add the fields from r2 for fname, fdtype in _get_fieldspec(r2.dtype): # Have we seen the current name already ? # we need to rebuild this list every time names = list(name for name, dtype in ndtype) try: nameidx = names.index(fname) except ValueError: #... we haven't: just add the description to the current list ndtype.append((fname, fdtype)) else: # collision _, cdtype = ndtype[nameidx] if fname in key: # The current field is part of the key: take the largest dtype ndtype[nameidx] = (fname, max(fdtype, cdtype)) else: # The current field is not part of the key: add the suffixes, # and place the new field adjacent to the old one ndtype[nameidx:nameidx + 1] = [ (fname + r1postfix, cdtype), (fname + r2postfix, fdtype) ] # Rebuild a dtype from the new fields ndtype = np.dtype(ndtype) # Find the largest nb of common fields : # r1cmn and r2cmn should be equal, but... cmn = max(r1cmn, r2cmn) # Construct an empty array output = ma.masked_all((cmn + r1spc + r2spc,), dtype=ndtype) names = output.dtype.names for f in r1names: selected = s1[f] if f not in names or (f in r2names and not r2postfix and f not in key): f += r1postfix current = output[f] current[:r1cmn] = selected[:r1cmn] if jointype in ('outer', 'leftouter'): current[cmn:cmn + r1spc] = selected[r1cmn:] for f in r2names: selected = s2[f] if f not in names or (f in r1names and not r1postfix and f not in key): f += r2postfix current = output[f] current[:r2cmn] = selected[:r2cmn] if (jointype == 'outer') and r2spc: current[-r2spc:] = selected[r2cmn:] # Sort and finalize the output output.sort(order=key) kwargs = dict(usemask=usemask, asrecarray=asrecarray) return _fix_output(_fix_defaults(output, defaults), **kwargs) def _rec_join_dispatcher( key, r1, r2, jointype=None, r1postfix=None, r2postfix=None, defaults=None): return (r1, r2) @array_function_dispatch(_rec_join_dispatcher) def rec_join(key, r1, r2, jointype='inner', r1postfix='1', r2postfix='2', defaults=None): """ Join arrays `r1` and `r2` on keys. Alternative to join_by, that always returns a np.recarray. See Also -------- join_by : equivalent function """ kwargs = dict(jointype=jointype, r1postfix=r1postfix, r2postfix=r2postfix, defaults=defaults, usemask=False, asrecarray=True) return join_by(key, r1, r2, **kwargs)