Feature request: How Do I add a new variable to a data set?

[rpgoldman]

A common thing to want to do is to create a new DataArray and add it to an existing Dataset, but the answer does not seem to appear in the "How Do I?" list.

Thanks!

[dcherian]

ds["name"] = data_array Also see Dataset.assign

A pull request would be very welcome!

[rpgoldman]

OK, done. Per my comments, I don't have the ability to build and check the sphinx code, so please check before merging.

[rpgoldman]

@dcherian
I know it's kind of overloading this issue, but if you would also LMK if there's a clean way to do compound querying, the way one can in Pandas, I will also put in something about that.

foo = data_array.where(np.logical_and(other_data_array['bar'] == 12, other_data_array['baz'] < 22))

...is all I have come up with and this gets bloated and unreadable really quickly if there are multiple conjuncts. Infix conjunction seems not to work unless I take the .values of the data array subsets, which adds its own layer of bloat.

I figure this is something that lots of people will want to do, but it seems a lot harder than pd.DataFrame.query()

[mathause]

You can shorthen this using parantheses and &:

sel = (other_data_array['bar'] == 12) & (other_data_array['baz'] < 22)
foo = data_array.where(sel)

[rpgoldman]

@mathause Thank you! That never occurred to me.

I thought it was something wrong with the way I was using conjunction, but now I believe it was just a matter of operator precedence.