Formatting data array as strings?

[ahuang11]

https://github.com/pydata/xarray/discussions/5865#discussioncomment-1636647

I wonder if it's possible to implement a built-in function like: da.str.format("%.2f") or xr.string_format(da, "%.2f)

To wrap:

import xarray as xr

da = xr.DataArray([5., 6., 7.])
das = xr.DataArray("%.2f")
das.str % da

<xarray.DataArray (dim_0: 3)>
array(['5.00', '6.00', '7.00'], dtype='<U4')
Dimensions without coordinates: dim_0

[mathause]

I think that sounds sensible. The idea would be to wrap xr.DataArray.str.__mod__ in xr.DataArray.str.format. Are you interested in providing a PR?

[ahuang11]

Actually would xr.DataArray.str.format work? e.g. xr.DataArray([0, 1, 2]).str would raise an error right since it's int type?

[husainridwan]

Hi @TomNicholas , how do I contribute to this as an outreachy intern?

[TomNicholas]

Hi @alrho007 - thanks for your interest in contributing to xarray!

The code for the string accessor is in xarray/core/accessor_str.py. That's where you would need to make changes.

The idea would be to wrap xr.DataArray.str.mod in xr.DataArray.str.format.

@mathause could you expand on what you mean exactly? I'm new to this part of the codebase. There is already a .format method, are you talking about changing its behaviour?

xr.DataArray([0, 1, 2]).str would raise an error right since it's int type?

Also @ahuang11 this seems fine? Because the .str accessor doesn't actually perform a check that the passed data is a str type immediately?

[ahuang11]

Thanks for following up! It's been a while so I don't remember; feel free to disregard what I said.

[mathause]

I probably got this from a pandas issue/ pull request - but I can't remember where exactly - sorry...

[headtr1ck]

Found as an answer to a proposal PR: https://github.com/pydata/xarray/pull/7628#discussion_r1140211918

The solution is to use .str.format the other way around as you propose:

You can try das.str.format(da). Maybe you need to use {} instead of % in your format array.