allow passing a function to set_labels (which will pass labels through the function)

[gdementen]

The end goal is to make transforming axis labels easier. eg lowercase -> uppercase or the opposite

This is technically easy, but the difficulty is to find a nice syntax. Currently we have to write:

>>> arr = ndtest(3)
>>> arr.set_labels('a', [l.upper() for l in arr.a.labels])
a  A0  A1  A2
    0   1   2
>>> # or
>>> arr.set_labels('a', map(str.upper, arr.a.labels))
a  A0  A1  A2
    0   1   2

maybe this would do:

>>> arr.map_labels('a', str.upper)
a  A0  A1  A2
    0   1   2
>>> # or this
>>> arr.set_axes('a', a.str.upper())
a  A0  A1  A2
    0   1   2

Where the str namespace would contain most str operations vectorized :
capitalize, casefold, center, count, encode, endswith, expandtabs, find, format, format_map, index, isalnum, isalpha, isdecimal, isdigit, isidentifier, islower, isnumeric, isprintable, isspace, istitle, isupper, join, ljust, lower, lstrip, maketrans, partition, replace, rfind, rindex, rjust, rpartition, rsplit, rstrip, split, splitlines, startswith, strip, swapcase, title, translate, upper, zfill

I think we will need the later at some point anyway, so the question is whether it is worth having the first one too to avoid having to repeat the axis name.

[alixdamman]

We could make the labels argument of LArray.set_labels accepting a function as value. The passed function will be applied to each label. This implies to also update the Axis.replace method.

[gdementen]

@alixdamman good idea, I like it! Let's go for that. We'll probably need the .str namespace later anyway but at least we are avoiding map_labels.