Source code for gmxapi.datamodel

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"""gmxapi data types and interfaces.
"""

__all__ = ['ndarray', 'NDArray']

import collections

import gmxapi.abc
from gmxapi import exceptions


class NDArray(gmxapi.abc.NDArray):
    """N-Dimensional array type.
    """

    def __init__(self, data=None):
        self._values = []
        self.dtype = None
        self.shape = ()
        if data is not None:
            if hasattr(data, 'result') or (
                    isinstance(data, collections.abc.Iterable) and any([hasattr(item, 'result') for item in data])):
                raise exceptions.ValueError(
                    'Make a Future of type NDArray instead of NDArray of type Future, or call result() first.')
            if isinstance(data, (str, bytes)):
                data = [data]
                length = 1
            else:
                try:
                    length = len(data)
                except TypeError:
                    # data is a scalar
                    length = 1
                    data = [data]
            self._values = data
            if length > 0:
                self.dtype = type(data[0])
                self.shape = (length,)

    def to_list(self):
        return self._values

    def __getitem__(self, i: int):
        return self._values[i]

    def __len__(self) -> int:
        return len(self._values)


def ndarray(data=None, shape=None, dtype=None):
    """Create an NDArray object from the provided iterable.

    Arguments:
        data: object supporting sequence, buffer, or Array Interface protocol

    ..  versionadded:: 0.1
        *shape* and *dtype* parameters

    If ``data`` is provided, ``shape`` and ``dtype`` are optional. If ``data`` is not
    provided, both ``shape`` and ``dtype`` are required.

    If ``data`` is provided and shape is provided, ``data`` must be compatible with
    or convertible to ``shape``. See Broadcast Rules in `datamodel` documentation.

    If ``data`` is provided and ``dtype`` is not provided, data type is inferred
    as the narrowest scalar type necessary to hold any element in ``data``.
    ``dtype``, whether inferred or explicit, must be compatible with all elements
    of ``data``.

    The returned object implements the gmxapi N-dimensional Array Interface.
    """
    if data is None:
        array = NDArray()
    else:
        if isinstance(data, NDArray):
            return data
        # data is not None, but may still be an empty sequence.
        length = 0
        try:
            length = len(data)
        except TypeError:
            # data is a scalar
            length = 1
            data = [data]
        array = NDArray(data)
    return array