Update copy_volume.py

[martinschorb]

needs to be converted to str, otherwise if is determined from data, it will fail with:

    dtype = "u" + dtype
TypeError: can only concatenate str (not "numpy.dtype[int8]") to str

see mobie/mobie-utils-python#57

[martinschorb]

would you also want to add a test for extracting the dtype from the raw data and then converting it?

[constantinpape]

Thanks, I will merge once the tests pass.

[constantinpape]

would you also want to add a test for extracting the dtype from the raw data and then converting it?

Not quite sure what you mean by this, but I already have a test that checks that int_to_uint works:
https://github.com/constantinpape/cluster_tools/blob/master/test/downscaling/test_downscaling.py#L183

[martinschorb]

Yes, other than over at mobie it looks like the scenario that a np.dtype object ends up in this string concatenation doe not happen here. So no need to test for it.

[constantinpape]

Yes, other than over at mobie it looks like the scenario that a np.dtype object ends up in this string concatenation doe not happen here. So no need to test for it.

Whether this is a string or a np dtype depends on the underlying store that is returned by elf.io.open_file. Since open_file is a very thin wrapper it's not possible to unify this.

Anyways, the fix here is very simple and with it support for np dtypes should be ensured, we don't need to add extra tests for this case.

Tests pass so I will merge now, thanks!