Error adding rowlabels for custom gridspec

[Holmgren825]

Hey!
Will begin by thanking you for continuing the work with ultraplot!

I've encountered what I think is an error with the formatting of row labels using a custom gridspec. If the first column of a row is empty, the row does not seem to count. Here is a minimal example:

import ultraplot as plt
gridspec = [
    [1, 1, 2, 2],
    [0, 3, 3, 0],
    [4, 4, 5, 5],
]

fig, ax = plt.subplots(
    gridspec,
)
ax.format(rowlabels=["1", "2", "3"])

which raises an error: ValueError: Got 3 left labels but found 2 axes along the left side of the figure.

If I add a plot to the first column of the 2nd row, things works as expected.

gridspec = [
    [1, 1, 2, 2],
    [6, 3, 3, 0],
    [4, 4, 5, 5],
]

fig, ax = plt.subplots(
    gridspec,
)
ax.format(rowlabels=["1", "2", "3"])

produces

[cvanelteren]

Thanks axs = self._get_align_axes(side) function is causing the issue (part of figure.py)

[cvanelteren]

The labeling does expect a grid, but do you want the label to appear immediate to the left or still on the outside grid? That is does the label for plot 3 need to be offset to the outside rectangle?

[Holmgren825]

I think that I would prefer the row labels to be vertically aligned (it is what I'm currently trying out manually placing a text annotation.)

Edit: So basically like the working example above, but without the extra subplot.

[cvanelteren]

I can see how we can allow row labels but col labels in this example is not trivial.

[cvanelteren]

For example let's say we have

[[1, 1, 2, 2], [0, 3 ,3 , 0], [4, 5, 6, 7]]

where should the top labels be placed?

[Holmgren825]

Yes that is a good question. For me, row/collabels are useful when there is something shared among them, maybe they belong to a group. So for the latest example, maybe top labels doesn't make sense?

To be consistent, perhaps being able to place labels according to the number of rows/cols reported by the axes object should work? For the example above I would've placed them at the bottom in that case. But I guess one can complicate things even further with something like [[1, 1, 2, 2], [0, 3 ,3 , 0], [4, 5, 6, 7]] where placing labels at the bottom wont work either.

[cvanelteren]

see #376

[cvanelteren]

We can allow for placing it on the left but error on the rest in the case I provided.

[cvanelteren]

e.g. this works:

[[1, 1, 2, 2], [0, 3 ,3 , 0], [4, 5, 6, 7]]

for left but no top (when n = 3) or bottom labels (n = 3 unless n = 5)

[cvanelteren]

I think it makes most sense if we "view" the labels as putting them on the axis that you hit first as if you were looking from the side of the grid, i.e.:

[cvanelteren]

So in this case:

You have 4 viewing from the right but 3 viewing from the left.