"Minor" longitude and latitude gridlines

[bradyrx]

Is there any straight forward way to stride through what tick labels are shown in cartopy? Or could this be added as a feature?

This would be the equivalent of having xticks=[0,5,10,15,20] + xticklabels=['0', '', '10', '', '20'] for instance. The idea here is especially in longitude when labels get packed and overlapped at a reasonable font size for folks to see.

import numpy as np
import proplot as plot

plot.rc['geogrid.linestyle'] = ':'
plot.rc['geogrid.linewidth'] = 2
plot.rc['geogrid.color'] = '#d3d3d3'

data = np.random.rand(90, 180)
lon = np.linspace(-179.5, 179.5, 180)
lat = np.linspace(-89.5, 89.5, 90)

f, ax = plot.subplots(width='12cm', aspect=4, proj='cyl', tight=True,)

p = ax.pcolormesh(lon, lat, data, )

ax.format(latlim=(20,50), lonlim=(-135, -105), land=True,
          latlines=plot.arange(20,50,5), lonlines=plot.arange(-135,-105, 5),
          labels=True)

ax.colorbar(p, loc='r')

This case doesn't have any issues, but imagine if you wanted the label size to be 14, 16, or 18 point font for a poster. All the lon labels overlap. Any way to show just 130W, 120W, 110W but maintain the grid structure? I figure there's a means to do it with the formatter/ticker, but I can't figure it out..

[lukelbd]

Makes sense to me -- having labeled and unlabeld gridlines would be analogous to having "major" and "minor" ticklines. You could do something like lonlines=10 with minorlonlines=5. I'll implement it when I get the chance -- will just require drawing two gridliner objects.

[bradyrx]

FYI @lukelbd, it looks like the minorlonlines keyword is gone from Axes.format. And there is no plot.rc.['gridminor.lonstep'] to access. I can't find any path forward to declare the minor grid line stepping/labeling in the current version.

[lukelbd]

Hmm not sure that was ever a feature. Can you point to a commit? For now you can do this manually using the cartopy Gridliner.

[bradyrx]

Oops I think I read your comment as if that was a hacky workaround with the current infrastructure.