Adding a `xmap.plot("color")` method

[argerlt]

I think the Phase class should have some sort of method for creating colormaps within the class.

currently, we do this (just like MTEX does)

import orix.data as oda
import orix.plot as opl
import orix.vector as ove

xmap = oda.sdss_ferrite_austenite(allow_download=True)
ckey_m3m = opl.IPFColorKeyTSL(
    xmap.phases["austenite"].point_group, direction=ove.Vector3d.zvector()
)
rgb_au = ckey_m3m.orientation2color(xmap["austenite"].orientations)
rgb_fe = ckey_m3m.orientation2color(xmap["ferrite"].orientations)
xmap['ferrite'].plot(rgb_fe)

Which works well enough, but being able to just directly do

xmap = oda.sdss_ferrite_austenite(allow_download=True)
xmap.plot('tsl')

would (I think) be better.

Open question on if it should be an addition to Phase, or a function in orix.plot.CrystalMapPlot. Former seems more useful, since it can be used for simplifying IPF plots as well, but the latter is maybe better from a "dividing up modules" point of view.

[hakonanes]

I agree with the general statement that doing some things could be simpler!

xmap.plot('tsl')

What would you expect to happen in this case?

This is the current signature:

def plot(
    self,
    value: np.ndarray | str | None = None,
    overlay: str | np.ndarray | None = None,
    ...
    **kwargs,
) -> mfigure.Figure | None:

And descriptions:

value
    An array or an attribute string to plot. If not given, a phase map is plotted.
overlay
    Name of map property or a property array to use in the alpha (RGBA) channel.
    The property range is adjusted for maximum contrast. Not used if not given.

If the crystal map has an attribute named "tsl", calling xmap.plot("tsl") should color each pixel by that attribute.

Therefore, I don't think adding a special meaning to a "tsl" string is possible. But, we could add convenience functions to achieve what you have in mind.

[argerlt]

I agree, xmap.plot('tsl') is problematic. Better option would be a child class xmap.IPFplot() with a cmap option.

I'm also leaning towards creating a Phase._colormap value that is an opl.IPFColorKeyTSL instance, along with a getter and setter, but if the implementation ends up getting to complex (do you autogenerate? do you let the user change the IPF reference direction? do you regenerate if the Phase changes? etc.), I will just fall back on having one of the inputs for IPFplot be a colorkey.

[hakonanes]

What we could do is to create a convenience function that returns the full RGB array that can then be passed to CrystalMap.plot(rgb), something like this:

# Load crystal map, xmap

import orix.plot as opl

rgb = opl.xmap2color(xmap, direction=[0, 0, 1])
xmap.plot(rgb)

This means just one extra line compared to xmap.plot("tsl"). But, no existing API has to change.

Would this work for you?

[argerlt]

Oh yeah, I like that suggestion. Let's do that.

[hakonanes]

And for the sake of trying to keep modules decoupled (they're currently quite coupled), we should add it as a function in the plot module (where the color key lives), rather than adding a method to the crystal map.