Function stack_arrays

numpy/lib/recfunctions.py:1324–1408

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 Whethe

(arrays, defaults=None, usemask=True, asrecarray=False,
                 autoconvert=False)

@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 an 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
    --------
    >>> import numpy as np
    >>> 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', 1e+20, 1e+20),
                dtype=[('A', 'S3'), ('B', '<f8'), ('C', '<f8')])

    """
    if isinstance(arrays, np.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)