104 lines
2.7 KiB
Python
104 lines
2.7 KiB
Python
# This file is part of h5py, a Python interface to the HDF5 library.
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#
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# http://www.h5py.org
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#
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# Copyright 2008-2013 Andrew Collette and contributors
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#
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# License: Standard 3-clause BSD; see "license.txt" for full license terms
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# and contributor agreement.
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"""
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Implements a portion of the selection operations.
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"""
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import numpy as np
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from .. import h5s
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def read_dtypes(dataset_dtype, names):
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""" Returns a 2-tuple containing:
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1. Output dataset dtype
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2. Dtype containing HDF5-appropriate description of destination
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"""
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if len(names) == 0: # Not compound, or all fields needed
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format_dtype = dataset_dtype
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elif dataset_dtype.names is None:
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raise ValueError("Field names only allowed for compound types")
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elif any(x not in dataset_dtype.names for x in names):
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raise ValueError("Field does not appear in this type.")
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else:
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format_dtype = np.dtype([(name, dataset_dtype.fields[name][0]) for name in names])
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if len(names) == 1:
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# We don't preserve the field information if only one explicitly selected.
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output_dtype = format_dtype.fields[names[0]][0]
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else:
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output_dtype = format_dtype
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return output_dtype, format_dtype
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def read_selections_scalar(dsid, args):
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""" Returns a 2-tuple containing:
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1. Output dataset shape
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2. HDF5 dataspace containing source selection.
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Works for scalar datasets.
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"""
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if dsid.shape != ():
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raise RuntimeError("Illegal selection function for non-scalar dataset")
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if args == ():
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# This is a signal that an array scalar should be returned instead
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# of an ndarray with shape ()
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out_shape = None
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elif args == (Ellipsis,):
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out_shape = ()
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else:
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raise ValueError("Illegal slicing argument for scalar dataspace")
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source_space = dsid.get_space()
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source_space.select_all()
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return out_shape, source_space
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class ScalarReadSelection:
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"""
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Implements slicing for scalar datasets.
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"""
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def __init__(self, fspace, args):
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if args == ():
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self.mshape = None
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elif args == (Ellipsis,):
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self.mshape = ()
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else:
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raise ValueError("Illegal slicing argument for scalar dataspace")
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self.mspace = h5s.create(h5s.SCALAR)
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self.fspace = fspace
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def __iter__(self):
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self.mspace.select_all()
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yield self.fspace, self.mspace
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def select_read(fspace, args):
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""" Top-level dispatch function for reading.
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At the moment, only supports reading from scalar datasets.
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"""
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if fspace.shape == ():
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return ScalarReadSelection(fspace, args)
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raise NotImplementedError()
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