NPZ ?

[vincentsarago]

What about Numpy multiple arrays https://numpy.org/doc/stable/reference/generated/numpy.savez_compressed.html

I added it to rio-tiler (ref: cogeotiff/rio-tiler#308). Storing multiple arrays is something I usually do by default (data + mask), but with the .NPY format I usually happen the mask in the data array (quite a hack IMO). With the NPZ format, the arrays can be stored in a separate way

import numpy as np

arr = np.random.randint(0, 255, size=(3, 512, 512), dtype=np.uint8)
mask = np.zeros((512, 512), dtype=np.uint8)

np.savez_compressed("test.npz", data=arr, mask=mask)
arrz = np.load("test.npz")
print(arrz.files)
>> ['data', 'mask']

data, mask = arrz["data"], arrz["mask"]