dask.array.to_npy_stack

dask.array.to_npy_stack(dirname, x, axis=0)

Write dask array to a stack of .npy files

This partitions the dask.array along one axis and stores each block along that axis as a single .npy file in the specified directory

Warning

This format uses the pickle module to serialize array metadata. The pickle module is not secure. Only load .npy stacks you trust.

See also

from_npy_stack

Examples

>>> x = da.ones((5, 10, 10), chunks=(2, 4, 4))
>>> da.to_npy_stack('data/', x, axis=0)

The .npy files store numpy arrays for x[0:2], x[2:4], and x[4:5] respectively, as is specified by the chunk size along the zeroth axis:

$ tree data/
data/
|-- 0.npy
|-- 1.npy
|-- 2.npy
|-- info

The info file stores the dtype, chunks, and axis information of the array. You can load these stacks with the dask.array.from_npy_stack() function.

>>> y = da.from_npy_stack('data/')