After installing ArviZ in the obvious way (conda install -c conda-forge arviz), I get the following failure. If anyone could shed light on what to do to fix this, that would be great.
>>> import arviz as az
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/igor/anaconda3/lib/python3.7/site-packages/arviz/__init__.py", line 32, in <module>
from .data import *
File "/Users/igor/anaconda3/lib/python3.7/site-packages/arviz/data/__init__.py", line 2, in <module>
from .base import CoordSpec, DimSpec, dict_to_dataset, numpy_to_data_array
File "/Users/igor/anaconda3/lib/python3.7/site-packages/arviz/data/base.py", line 10, in <module>
import xarray as xr
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/__init__.py", line 3, in <module>
from . import testing, tutorial, ufuncs
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/testing.py", line 8, in <module>
from xarray.core import duck_array_ops, formatting, utils
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/core/duck_array_ops.py", line 15, in <module>
from . import dask_array_compat, dask_array_ops, dtypes, npcompat, nputils
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/core/dask_array_compat.py", line 5, in <module>
from .pycompat import dask_version
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/core/pycompat.py", line 55, in <module>
dsk = DuckArrayModule("dask")
File "/Users/igor/anaconda3/lib/python3.7/site-packages/xarray/core/pycompat.py", line 25, in __init__
duck_array_type = (import_module("dask.array").Array,)
File "/Users/igor/anaconda3/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "/Users/igor/anaconda3/lib/python3.7/site-packages/dask/array/__init__.py", line 3, in <module>
from . import backends, fft, lib, linalg, ma, overlap, random
File "/Users/igor/anaconda3/lib/python3.7/site-packages/dask/array/fft.py", line 13, in <module>
from .core import concatenate as _concatenate
File "/Users/igor/anaconda3/lib/python3.7/site-packages/dask/array/core.py", line 20, in <module>
from fsspec import get_mapper
File "/Users/igor/anaconda3/lib/python3.7/site-packages/fsspec/__init__.py", line 13, in <module>
from .core import get_fs_token_paths, open, open_files, open_local
File "/Users/igor/anaconda3/lib/python3.7/site-packages/fsspec/core.py", line 18, in <module>
from .compression import compr
File "/Users/igor/anaconda3/lib/python3.7/site-packages/fsspec/compression.py", line 139, in <module>
snappy.compress
AttributeError: module 'snappy' has no attribute 'compress'
Following the suggestion of @merv, I get the following, which explains the problem (it is a different package called snappy, for computational topology). But how do I fix it (the obvious solution is to have a different environment, but I am a bit puzzled as to how it is possible to have two pypi packages with the same name to begin with.
# packages in environment at /Users/igor/anaconda3:
#
# Name Version Build Channel
arviz 0.11.2 pyhd8
dask 2021.8.0 pyhd3eb1b0_0
dask-core 2021.8.0 pyhd3eb1b0_0
fsspec 2021.7.0 pyhd3eb1b0_0
snappy 3.0.1 pypi_0 pypi
snappy-15-knots 1.1 pypi_0 pypi
snappy-manifolds 1.1.2 pypi_0 pypi
xarray 0.19.0 pyhd3eb1b0_1
Looking at the installed packages, you don't have python-snappy installed. I just verified that installing it seems to get it working, although you are right that technically python-snappy and snappy are colliding into the module namespace snappy.
conda install python-snappy
or
pip install python-snappy
As you mentioned, it might be better to simply use a new environment, and avoid having snappy and python-snappy installed in the same one.