Plot SVGs are massive in size due to color legend

[dnjst]

Describe the bug
I would like to make publication-quality editable figures of LIANA plots in SVG format, but am coming up an obstacle where the output SVG files are massive in size (~2 MB) and thus cause memory issues and crashing when loaded into a program such as powerpoint/illustrator, and even inkscape struggles.

The reason seems to be that the color bar legend for the annotation colors (here "magnitude_rank") is made up of thousands of tiny rectangles which is blowing up the number of points in the SVG.

This may be a plotnine issue, but perhaps you could look into it and maybe suggest a workaround?

For instance, although not ideal, is it possible to optionally rasterize the colorbar and leave the rest as SVG, like how scanpy does with UMAPs of thousands of points?

I will also look in how to report/address this upstream if necessary...

To Reproduce
my_plot = li.pl.dotplot(adata = adata,
colour='magnitude_rank',
inverse_colour=True,
size='specificity_rank',
inverse_size=True,
source_labels=['CD34+', 'CD56+ NK', 'CD14+ Monocyte'],
target_labels=['CD34+', 'CD56+ NK'],
filter_fun=lambda x: x['specificity_rank'] <= 0.01,
)
my_plot.save("myfigure.svg", transparent=True)

Screenshots
If applicable, add screenshots with a traceback to any exception.

[dbdimitrov]

Hi @dnjst,

Indeed, this is purely on the plotnine side, but I found a way to rasterize the colour guide:

p2 = p + p9.guides(color=p9.guide_colorbar(display='raster', nbin=50))
p2.save('test2.pdf', dpi=300)

However, for some reason in my case it would move the colour bar whenever I tried to load it into inkscape... So, if this happens to you, you would have to drag it back 😅 😅 😅 Not sure if this is a plotnine or an inkscape 'feature'.

I used plotnine == '0.13.3'. I also tried with other 0.13.x versions but it did not resolve the shifting, while older versions have a different API and did not actually rasterize it...

Genuinely future liana versions should transition to matplotlib completely.

[dnjst]

Thanks for the code - yes I tried that and my experience was it saved the filesize blowing up issue, but it moved the colorbar to the bottom left corner also!