tensorlayer/prepro.py
def pad_sequences(sequences, maxlen=None, dtype='int32', padding='post', truncating='pre', value=0.):
    """Pads each sequence to the same length:
    the length of the longest sequence.
    If maxlen is provided, any sequence longer
    than maxlen is truncated to maxlen.
    Truncation happens off either the beginning (default) or
    the end of the sequence.
    Supports post-padding and pre-padding (default).

    Parameters
    ----------
    sequences : list of list of int
        All sequences where each row is a sequence.
    maxlen : int
        Maximum length.
    dtype : numpy.dtype or str
        Data type to cast the resulting sequence.
    padding : str
        Either 'pre' or 'post', pad either before or after each sequence.
    truncating : str
        Either 'pre' or 'post', remove values from sequences larger than maxlen either in the beginning or in the end of the sequence
    value : float
        Value to pad the sequences to the desired value.

    Returns
    ----------
    x : numpy.array
        With dimensions (number_of_sequences, maxlen)

    Examples
    ----------
    >>> sequences = [[1,1,1,1,1],[2,2,2],[3,3]]
    >>> sequences = pad_sequences(sequences, maxlen=None, dtype='int32',
    ...                  padding='post', truncating='pre', value=0.)
    [[1 1 1 1 1]
     [2 2 2 0 0]
     [3 3 0 0 0]]

    """
    lengths = [len(s) for s in sequences]

    nb_samples = len(sequences)
    if maxlen is None:
        maxlen = np.max(lengths)

    # take the sample shape from the first non empty sequence
    # checking for consistency in the main loop below.
    sample_shape = tuple()
    for s in sequences:
        if len(s) > 0:
            sample_shape = np.asarray(s).shape[1:]
            break

    x = (np.ones((nb_samples, maxlen) + sample_shape) * value).astype(dtype)
    for idx, s in enumerate(sequences):
        if len(s) == 0:
            continue  # empty list was found
        if truncating == 'pre':
            trunc = s[-maxlen:]
        elif truncating == 'post':
            trunc = s[:maxlen]
        else:
            raise ValueError('Truncating type "%s" not understood' % truncating)

        # check `trunc` has expected shape
        trunc = np.asarray(trunc, dtype=dtype)
        if trunc.shape[1:] != sample_shape:
            raise ValueError(
                'Shape of sample %s of sequence at position %s is different from expected shape %s' %
                (trunc.shape[1:], idx, sample_shape)
            )

        if padding == 'post':
            x[idx, :len(trunc)] = trunc
        elif padding == 'pre':
            x[idx, -len(trunc):] = trunc
        else:
            raise ValueError('Padding type "%s" not understood' % padding)
    return x.tolist()
def pad_sequences(sequences, maxlen=None, dtype='int32', padding='post', truncating='pre', value=0.):
    """Pads each sequence to the same length:
    the length of the longest sequence.
    If maxlen is provided, any sequence longer
    than maxlen is truncated to maxlen.
    Truncation happens off either the beginning (default) or
    the end of the sequence.
    Supports post-padding and pre-padding (default).

    Parameters
    ----------
    sequences : list of list of int
        All sequences where each row is a sequence.
    maxlen : int
        Maximum length.
    dtype : numpy.dtype or str
        Data type to cast the resulting sequence.
    padding : str
        Either 'pre' or 'post', pad either before or after each sequence.
    truncating : str
        Either 'pre' or 'post', remove values from sequences larger than maxlen either in the beginning or in the end of the sequence
    value : float
        Value to pad the sequences to the desired value.

    Returns
    ----------
    x : numpy.array
        With dimensions (number_of_sequences, maxlen)

    Examples
    ----------
    >>> sequences = [[1,1,1,1,1],[2,2,2],[3,3]]
    >>> sequences = pad_sequences(sequences, maxlen=None, dtype='int32',
    ...                  padding='post', truncating='pre', value=0.)
    [[1 1 1 1 1]
     [2 2 2 0 0]
     [3 3 0 0 0]]

    """
    lengths = [len(s) for s in sequences]

    nb_samples = len(sequences)
    if maxlen is None:
        maxlen = np.max(lengths)

    # take the sample shape from the first non empty sequence
    # checking for consistency in the main loop below.
    sample_shape = tuple()
    for s in sequences:
        if len(s) > 0:
            sample_shape = np.asarray(s).shape[1:]
            break

    x = (np.ones((nb_samples, maxlen) + sample_shape) * value).astype(dtype)
    for idx, s in enumerate(sequences):
        if len(s) == 0:
            continue  # empty list was found
        if truncating == 'pre':
            trunc = s[-maxlen:]
        elif truncating == 'post':
            trunc = s[:maxlen]
        else:
            raise ValueError('Truncating type "%s" not understood' % truncating)

        # check `trunc` has expected shape
        trunc = np.asarray(trunc, dtype=dtype)
        if trunc.shape[1:] != sample_shape:
            raise ValueError(
                'Shape of sample %s of sequence at position %s is different from expected shape %s' %
                (trunc.shape[1:], idx, sample_shape)
            )

        if padding == 'post':
            x[idx, :len(trunc)] = trunc
        elif padding == 'pre':
            x[idx, -len(trunc):] = trunc
        else:
            raise ValueError('Padding type "%s" not understood' % padding)
    return x.tolist()
Pads each sequence to the same length:
    the length of the longest sequence.
    If maxlen is provided, any sequence longer
    than maxlen is truncated to maxlen.
    Truncation happens off either the beginning (default) or
    the end of the sequence.
    Supports post-padding and pre-padding (default).

    Parameters
    ----------
    sequences : list of list of int
        All sequences where each row is a sequence.
    maxlen : int
        Maximum length.
    dtype : numpy.dtype or str
        Data type to cast the resulting sequence.
    padding : str
        Either 'pre' or 'post', pad either before or after each sequence.
    truncating : str
        Either 'pre' or 'post', remove values from sequences larger than maxlen either in the beginning or in the end of the sequence
    value : float
        Value to pad the sequences to the desired value.

    Returns
    ----------
    x : numpy.array
        With dimensions (number_of_sequences, maxlen)

    Examples
    ----------
    >>> sequences = [[1,1,1,1,1],[2,2,2],[3,3]]
    >>> sequences = pad_sequences(sequences, maxlen=None, dtype='int32',
    ...                  padding='post', truncating='pre', value=0.)
    [[1 1 1 1 1]
     [2 2 2 0 0]
     [3 3 0 0 0]]