Updates to upsampling, downsampling, level, and other fixes (#12)

* updates to upsampling, and adds rechunk again
as was getting errors without it..

* changed behaviour of level selected in from_path()

- now also applies downsampling (in xy and z) if necessary
- also supports level > max_level

* updates for passing storage_options and path as store

* update downsample func, move static methods

downsample() now takes level as an argument, and has an option do_normalized_sum, which is used for field fraction calculation
TODO: use member variable for the z_level_offset

also moved a couple global helper functions to staticmethods

* limit to python3.10 or greater (| in type hints)

- remove unnecessary normalized sum (same as mean) in downsample
- add simple downsample test

pyproject.toml

@@ -10,7 +10,7 @@ packages = [{include = "zarrnii"}]
 
 
 [tool.poetry.dependencies]
-python = ">=3.9,<4.0"
+python = ">=3.10,<4.0"
 zarr = "^2.17.0"
 nibabel = "^5.2.0"
 dask = "^2024.2.0"

tests/test_downsample.py

@@ -0,0 +1,18 @@
+from test_io import nifti_nib, cleandir
+import pytest
+import numpy as np
+from numpy.testing import assert_array_almost_equal, assert_array_equal
+from zarrnii import ZarrNii
+
+@pytest.mark.usefixtures("cleandir")
+def test_downsample(nifti_nib):
+
+    nifti_nib.to_filename("test.nii")
+    znimg = ZarrNii.from_path("test.nii")
+
+    ds=np.array([2,5,8])
+    znimg_downsampled = znimg.downsample(along_x=ds[0],along_y=ds[1],along_z=ds[2])
+
+    #check size is same as expected size
+    assert_array_equal(znimg.darr.shape[1:],znimg_downsampled.darr.shape[1:] * ds)
+