Delta

class numcodecs.delta.Delta(dtype, astype=None)

Codec to encode data as the difference between adjacent values.

Parameters:

dtype : dtype

Data type to use for decoded data.

astype : dtype, optional

Data type to use for encoded data.

Notes

If astype is an integer data type, please ensure that it is sufficiently large to store encoded values. No checks are made and data may become corrupted due to integer overflow if astype is too small. Note also that the encoded data for each chunk includes the absolute value of the first element in the chunk, and so the encoded data type in general needs to be large enough to store absolute values from the array.

Examples

>>> import numcodecs
>>> import numpy as np
>>> x = np.arange(100, 120, 2, dtype='i8')
>>> codec = numcodecs.Delta(dtype='i8', astype='i1')
>>> y = codec.encode(x)
>>> y
array([100,   2,   2,   2,   2,   2,   2,   2,   2,   2], dtype=int8)
>>> z = codec.decode(y)
>>> z
array([100, 102, 104, 106, 108, 110, 112, 114, 116, 118])
codec_id = 'delta'