# numpy.unpackbits

numpy.unpackbits(a, /, axis=None, count=None, bitorder='big')

  Unpacks elements of a uint8 array into a binary-valued output array.

  Each element of a represents a bit-field that should be unpacked into a binary-valued output array. The shape of the output array is either 1-D (if axis is `None`) or the same shape as the input array with unpacking done along the axis specified.

  Parameters
    a ndarray, uint8 type

      Input array.

    axis int, optional

      The dimension over which bit-unpacking is done. `None` implies unpacking the flattened array.

    count int or None, optional

      The number of elements to unpack along axis, provided as a way of undoing the effect of packing a size that is not a multiple of eight. A non-negative number means to only unpack count bits. A negative number means to trim off that many bits from the end. `None` means to unpack the entire array (the default). Counts larger than the available number of bits will add zero padding to the output. Negative counts must not exceed the available number of bits.

      New in version 1.17.0.

    bitorder{‘big’, ‘little’}, optional

      The order of the returned bits. ‘big’ will mimic bin(val), `3 = 0b00000011 => [0, 0, 0, 0, 0, 0, 1, 1]`, ‘little’ will reverse the order to `[1, 1, 0, 0, 0, 0, 0, 0]`. Defaults to ‘big’.

      New in version 1.17.0.

  Returns
    unpacked ndarray, uint8 type

      The elements are binary-valued (0 or 1).

  See also

  `packbits`

    Packs the elements of a binary-valued array into bits in a uint8 array.

  Examples

      >>> a = np.array([[2], [7], [23]], dtype=np.uint8)
      >>> a
      array([[ 2],
             [ 7],
             [23]], dtype=uint8)
      >>> b = np.unpackbits(a, axis=1)
      >>> b
      array([[0, 0, 0, 0, 0, 0, 1, 0],
             [0, 0, 0, 0, 0, 1, 1, 1],
             [0, 0, 0, 1, 0, 1, 1, 1]], dtype=uint8)
      >>> c = np.unpackbits(a, axis=1, count=-3)
      >>> c
      array([[0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0],
             [0, 0, 0, 1, 0]], dtype=uint8)

      >>> p = np.packbits(b, axis=0)
      >>> np.unpackbits(p, axis=0)
      array([[0, 0, 0, 0, 0, 0, 1, 0],
             [0, 0, 0, 0, 0, 1, 1, 1],
             [0, 0, 0, 1, 0, 1, 1, 1],
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0]], dtype=uint8)
      >>> np.array_equal(b, np.unpackbits(p, axis=0, count=b.shape[0]))
      True

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