How to run math operations on Zarr

[meteoDaniel]

Dear all,

I have created a native Zarr using zarr.open() and wrote data into it.

Afterwards I want to run calculations on that zarr, in the same way as I would do with numpy but receive:

zarr TypeError: unsupported operand type(s) for -: 'Array' and 'float'

Edit:
I want to avoid loading all the data into ram.

Any thoughts how to work around that issue?

[dcherian]

You have to read the data first so eitehr np.array(zarr_array) - 1 or zarr_array[:] - 1 (I think)

[meteoDaniel]

But in that case, all the data will be load into memory and that is not what I want.

[dcherian]

Then use dask. dask.array.from_array(zarr_array) - 1