Plotting maxima & minima, lows & highs, etc

[rolypolyman]

I just need a nudge in the right direction. Is there a built in function of some sort for plotting lows & highs, or maxima & minima (e.g. from vorticity), etc, given a 2D (or xarray) data field plotted on a horizontal cartopy map?

I tried writing my own function using something like this, after identifying highs and lows in the array:

ax.text(lon_2d[y, x], lat_2d[y, x], 'L', fontsize=24, fontweight='bold', ha='center', va='center', 
                    color='red', rotation=rotation, transform=data_crs)

It works but there's problems fitting it to the map window since the map is dynamically sized by matplotlib and cartopy. If I simply plot all the highs and lows it will literally try to plot all of them even if they are beyond the borders of the map, causing the map to resize and a lot of new whitespace will appear. I have had to resort to manually constraining highs and lows by hardcoded lat/long until I figure it out.

If this has been covered in MetPy Mondays I will be glad to have a look.

Thanks!

[sgdecker]

I think this example is what you are looking for. The functionality isn't built in yet, but there is work in that direction (#3110).

[rolypolyman]

Thank you, that helps... I just wanted to make sure I wasn't missing something obvious.

[kgoebber]

Yes, there is active work to make the finding and plotting of highs/lows (max/min) ongoing with an active issue #3110 in MetPy. The hope is to have that in for the next release of the package.

[dopplershift]

Just FYI that I made the hard choice to punt this from the release so we can get it out today. I'm still working on finishing off the algorithm, but there are some issues to resolve there plus and API for plotting I don't want to rush.