# Source code for tables.earray

    # -*- coding: utf-8 -*-

    ########################################################################
    #
    # License: BSD
    # Created: December 15, 2003
    # Author: Francesc Alted - faltet@pytables.com
    #
    # $Id$
    #
    ########################################################################

    """Here is defined the EArray class."""

    import numpy

    from tables.utils import convert_to_np_atom2, SizeType
    from tables.carray import CArray

    from tables._past import previous_api, previous_api_property

    # default version for EARRAY objects
    # obversion = "1.0"    # initial version
    # obversion = "1.1"    # support for complex datatypes
    # obversion = "1.2"    # This adds support for time datatypes.
    # obversion = "1.3"    # This adds support for enumerated datatypes.
    obversion = "1.4"    # Numeric and numarray flavors are gone.

    class EArray(CArray):
        """This class represents extendable, homogeneous datasets in an HDF5 file.

        The main difference between an EArray and a CArray (see
        :ref:`CArrayClassDescr`), from which it inherits, is that the former
        can be enlarged along one of its dimensions, the *enlargeable
        dimension*.  That means that the :attr:`Leaf.extdim` attribute (see
        :class:`Leaf`) of any EArray instance will always be non-negative.
        Multiple enlargeable dimensions might be supported in the future.

        New rows can be added to the end of an enlargeable array by using the
        :meth:`EArray.append` method.

        Parameters
        ----------
        parentnode
            The parent :class:`Group` object.

            .. versionchanged:: 3.0
               Renamed from *parentNode* to *parentnode*.

        name : str
            The name of this node in its parent group.

        atom
            An `Atom` instance representing the *type* and *shape*
            of the atomic objects to be saved.

        shape
            The shape of the new array.  One (and only one) of
            the shape dimensions *must* be 0.  The dimension being 0
            means that the resulting `EArray` object can be extended
            along it.  Multiple enlargeable dimensions are not supported
            right now.

        title
            A description for this node (it sets the ``TITLE``
            HDF5 attribute on disk).

        filters
            An instance of the `Filters` class that provides information
            about the desired I/O filters to be applied during the life
            of this object.

        expectedrows
            A user estimate about the number of row elements that will
            be added to the growable dimension in the `EArray` node.
            If not provided, the default value is ``EXPECTED_ROWS_EARRAY``
            (see ``tables/parameters.py``).  If you plan to create either
            a much smaller or a much bigger `EArray` try providing a guess;
            this will optimize the HDF5 B-Tree creation and management
            process time and the amount of memory used.

        chunkshape
            The shape of the data chunk to be read or written in a single
            HDF5 I/O operation.  Filters are applied to those chunks of data.
            The dimensionality of `chunkshape` must be the same as that of
            `shape` (beware: no dimension should be 0 this time!).
            If ``None``, a sensible value is calculated based on the
            `expectedrows` parameter (which is recommended).

        byteorder
            The byteorder of the data *on disk*, specified as 'little' or
            'big'. If this is not specified, the byteorder is that of the
            platform.

        Examples
        --------

        See below a small example of the use of the `EArray` class.  The
        code is available in ``examples/earray1.py``::

            import tables
            import numpy

            fileh = tables.open_file('earray1.h5', mode='w')
            a = tables.StringAtom(itemsize=8)

            # Use ``a`` as the object type for the enlargeable array.
            array_c = fileh.create_earray(fileh.root, 'array_c', a, (0,),
                                          \"Chars\")
            array_c.append(numpy.array(['a'*2, 'b'*4], dtype='S8'))
            array_c.append(numpy.array(['a'*6, 'b'*8, 'c'*10], dtype='S8'))

            # Read the string ``EArray`` we have created on disk.
            for s in array_c:
                print('array_c[%s] => %r' % (array_c.nrow, s))
            # Close the file.
            fileh.close()

        The output for the previous script is something like::

            array_c[0] => 'aa'
            array_c[1] => 'bbbb'
            array_c[2] => 'aaaaaa'
            array_c[3] => 'bbbbbbbb'
            array_c[4] => 'cccccccc'

        """

        # Class identifier.
        _c_classid = 'EARRAY'

        _c_classId = previous_api_property('_c_classid')

        # Special methods
        # ~~~~~~~~~~~~~~~
        def __init__(self, parentnode, name,
                     atom=None, shape=None, title="",
                     filters=None, expectedrows=None,
                     chunkshape=None, byteorder=None,
                     _log=True):

            # Specific of EArray
            if expectedrows is None:
                expectedrows = parentnode._v_file.params['EXPECTED_ROWS_EARRAY']
            self._v_expectedrows = expectedrows
            """The expected number of rows to be stored in the array."""

            # Call the parent (CArray) init code
            super(EArray, self).__init__(parentnode, name, atom, shape, title,
                                         filters, chunkshape, byteorder, _log)

        # Public and private methods
        # ~~~~~~~~~~~~~~~~~~~~~~~~~~
        def _g_create(self):
            """Create a new array in file (specific part)."""

            # Pre-conditions and extdim computation
            zerodims = numpy.sum(numpy.array(self.shape) == 0)
            if zerodims > 0:
                if zerodims == 1:
                    self.extdim = list(self.shape).index(0)
                else:
                    raise NotImplementedError(
                        "Multiple enlargeable (0-)dimensions are not "
                        "supported.")
            else:
                raise ValueError(
                    "When creating EArrays, you need to set one of "
                    "the dimensions of the Atom instance to zero.")

            # Finish the common part of the creation process
            return self._g_create_common(self._v_expectedrows)

        def _check_shape_append(self, nparr):
            "Test that nparr shape is consistent with underlying EArray."

            # The arrays conforms self expandibility?
            myrank = len(self.shape)
            narank = len(nparr.shape) - len(self.atom.shape)
            if myrank != narank:
                raise ValueError(("the ranks of the appended object (%d) and the "
                                  "``%s`` EArray (%d) differ")
                                 % (narank, self._v_pathname, myrank))
            for i in range(myrank):
                if i != self.extdim and self.shape[i] != nparr.shape[i]:
                    raise ValueError(("the shapes of the appended object and the "
                                      "``%s`` EArray differ in non-enlargeable "
                                      "dimension %d") % (self._v_pathname, i))

        _checkShapeAppend = previous_api(_check_shape_append)

        def append(self, sequence):
            """Add a sequence of data to the end of the dataset.

            The sequence must have the same type as the array; otherwise a
            TypeError is raised. In the same way, the dimensions of the
            sequence must conform to the shape of the array, that is, all
            dimensions must match, with the exception of the enlargeable
            dimension, which can be of any length (even 0!).  If the shape
            of the sequence is invalid, a ValueError is raised.

            """

            self._g_check_open()
            self._v_file._check_writable()

            # Convert the sequence into a NumPy object
            nparr = convert_to_np_atom2(sequence, self.atom)
            # Check if it has a consistent shape with underlying EArray
            self._check_shape_append(nparr)
            # If the size of the nparr is zero, don't do anything else
            if nparr.size > 0:
                self._append(nparr)

        def _g_copy_with_stats(self, group, name, start, stop, step,
                               title, filters, chunkshape, _log, **kwargs):
            """Private part of Leaf.copy() for each kind of leaf."""

            (start, stop, step) = self._process_range_read(start, stop, step)
            # Build the new EArray object
            maindim = self.maindim
            shape = list(self.shape)
            shape[maindim] = 0
            # The number of final rows
            nrows = len(xrange(0, stop - start, step))
            # Build the new EArray object
            object = EArray(
                group, name, atom=self.atom, shape=shape, title=title,
                filters=filters, expectedrows=nrows, chunkshape=chunkshape,
                _log=_log)
            # Now, fill the new earray with values from source
            nrowsinbuf = self.nrowsinbuf
            # The slices parameter for self.__getitem__
            slices = [slice(0, dim, 1) for dim in self.shape]
            # This is a hack to prevent doing unnecessary conversions
            # when copying buffers
            self._v_convert = False
            # Start the copy itself
            for start2 in xrange(start, stop, step * nrowsinbuf):
                # Save the records on disk
                stop2 = start2 + step * nrowsinbuf
                if stop2 > stop:
                    stop2 = stop
                # Set the proper slice in the extensible dimension
                slices[maindim] = slice(start2, stop2, step)
                object._append(self.__getitem__(tuple(slices)))
            # Active the conversion again (default)
            self._v_convert = True
            nbytes = numpy.prod(self.shape, dtype=SizeType) * self.atom.itemsize

            return (object, nbytes)

        _g_copyWithStats = previous_api(_g_copy_with_stats)

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