Array formatting fixes for sparse and NEP-18 arrays.

[shoyer]

I also did a bit of cleanup (e.g., renaming methods) in xarray.core.formatting.

Sparse arrays were previously not shown in the Dataset repr:

<xarray.Dataset>
Dimensions:  (x: 4)
Coordinates:
    y        (x) int64 ...
Dimensions without coordinates: x
Data variables:
    a        (x) float64 ..."""

Now they are:

<xarray.Dataset>
Dimensions:  (x: 4)
Coordinates:
    y        (x) int64 <COO: shape=(4,), nnz=3, fill_value=0>
Dimensions without coordinates: x
Data variables:
    a        (x) float64 <COO: shape=(4,), nnz=4, fill_value=0.0>"""

• Tests added
• Passes black . && mypy . && flake8

[pep8speaks]

Hello @shoyer! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file xarray/core/computation.py:

Line 962:89: E501 line too long (90 > 88 characters)

• In the file xarray/tests/test_dataarray.py:

Line 101:89: E501 line too long (91 > 88 characters)
Line 102:89: E501 line too long (95 > 88 characters)

• In the file xarray/tests/test_dataset.py:

Line 193:89: E501 line too long (91 > 88 characters)
Line 194:89: E501 line too long (89 > 88 characters)

Comment last updated at 2019-08-15 20:33:50 UTC

[max-sixty]

Suggested change

# need to insert str dtype at runtime to handle both Python 2 & 3

[shoyer]

we still need this for supporting different endiannesses

[crusaderky]

Possible improvements:

• Take a slice from the front of sparse arrays, densify it, and show the array contents just like you can see them for dense arrays
• Represent dask arrays differently when they have a sparse _meta

[shoyer]

• Take a slice from the front of sparse arrays, densify it, and show the array contents just like you can see them for dense arrays

This is a good idea, but it will require slightly more complex logic to pull items only from the front of an array. I don't have a lot of time to iterate on this right now, so I'm going to leave it for later.

Represent dask arrays differently when they have a sparse _meta

I have now added in meta to the repr for dask arrays. PTAL.

[crusaderky]

Re legacy dask: #3222