Color maps could look better

[lee1043]

Some of color maps have discrete colors at both edges. Instead of using range(16,240) for vcs.getcolors to avoid those edge colors, I think it would be much simple for users if we can make users no need to think about it.

Below code is for making above image:
plot.py.txt

[doutriaux1]

@lee1043 in order to have vcs revert to the old behaviour (range(16,240) simply add:

vcs.utils.defaultColorsRange = range(16,240)

At the begining of your script that should solve the issue for you

[durack1]

@lee1043 this is great, thanks for kicking this off.. I've been begging for this for a while CDAT/cdat#906 and #98

There seems to be quite a large number of dupes in the #238 (comment) above, so blue2green == blue_to_grn, blue2grey == blue_to_grey etc etc..

It also seems to be missing a large number of the palettes that @chaosphere2112 managed to find back in CDAT/cdat#1345 (comment), from @chaosphere2112's stuff, I also noted how many unique matplotlib colormaps were available, see CDAT/cdat#1345 (comment), plus all the additional colormaps that I provided through to @chaosphere2112 in CDAT/cdat#1345 (comment) (the bottom right thicker panels) which can be found in the file https://github.com/durack1/durolib/blob/master/lib/colourLib.py

Happy to iterate and tweak these alongside you..

And so we have everything in one place..

The matplotlib colormaps:

And the @chaosphere2112 maps from Dec 2015

[jypeter]

Thanks @lee1043 for the useful script! Some version of it would be useful in the gallery

Several color related questions for @doutriaux1 et al:

• do we still have something like the old x.colormapgui()? Or some kind of widget that would allow the user to browse the existing colormaps?
• I had never heard of x.util.*, eventhough some of the functions in there look familiar. Is this documented somewhere? I have failed to find something about this (and something recent about colormaps) in the uvcdat web site. Of course, the fact that there is no Search button did not help :( What happened to the Search field? cdat.github.io#129
• Is there an easy way to revert the order of colors in a colormap? eg I want ''rainbownogreen" for temperature and I need it in blue to red order?
• One of the major vcs limitations in the good old cgm/gks days (when plotting was easier and faster) was that you could only use 256 colors at a given time on a canvas, and I had to do a lot of custom colormaps generation. Is it possible now to use different colormaps for different plots on the same canvas

I have recently heard about a useful set of colormaps, with a matching nice documentation: http://matplotlib.org/cmocean/

[doutriaux1]

• @jypeter colormapgui() is dead, in the process of being re-implemented in vcdat
• @jypeter good point about vcs.utils, I will create an issue to make a jupyter notebook about it. readthedocs eventually will have it as well.
• just pass the reverted colors to the graphics method, example:

import vcs
gm = vcs.createisofill()
gm.colormap = "rainbow"
levels = [1,2,3,4,5]
colors = vcs.getcolors(levels,colors=range(255,-1,-1))
gm.fillareacolors=colors

• as demonstrated above, each graphic method can now have its own colormap, the colormap used is decide in this order: graphic_method -> canvas -> vcs module

import vcs
x=vcs.init()
gm=vcs.createisofill()
# First way setting colormap at vcs level
vcs._colorMap = "viridis"
# Second way at the canvas level
x.setcolormap("inferno")  # superseeds vcs colormap
# Third way at gm level
gm.colormap = "plasma"  # superseeds canvas

[lee1043]

@doutriaux1 Color shrinking for some horizontal bars is not dependent to selection of color map. See below. Should be something related to EzTemplate? Weird...

plot2.py.txt

[doutriaux1]

@lee1043 I think so, something in EzTemplate, althoguh template.data.x1 and template.data.x2 are constant. Sorry didn't have time to look at it yet.

[lee1043]

@durack1 @doutriaux1 @chaosphere2112

Maybe having matplotlib color maps in VCS related to below?

vcs.colors.matplotlib2vcs

https://uvcdat.llnl.gov/docs/vcs/misc/colors.html
https://uvcdat.llnl.gov/docs/_modules/vcs/colors.html

I will test it. Any comment welcome.

[lee1043]

@durack1 I believe below is that @chaosphere2112 was working on at CDAT/cdat#1345 (comment). Could use vcs.colors.matplotlib2vcs to get all available color maps from matplotlib.

Plotting code:
visualize_colormaps_matplotlib2.py.txt

[durack1]

@lee1043 I know that if you put a trailing _r on the matplotlib colormaps (so e.g. RdBu_r) you get the inverted colormap in this case the inverse of RdBu just FYI, I think this works for most colormaps

[doutriaux1]

@lee1043 I worte the code to convert mpl colormap so yes you can import mpl colormap. Not sure the _r trick will work though, it might be at plotting time kind of trick. Personally I still don't see the usefullness on having an inverted colormap when all you need to do is colors[::-1] once you got your colors...

[lee1043]

@durack1 @doutriaux1 I can load _r color maps from matplotlib and convert them to VCS as like they are independent color maps. Just didn't listed them on the image to avoid image becomes very long in vertical.

[lee1043]

@doutriaux1 @durack1 friendly reminder: it would be nice if we can have matplotlib colormaps already in it when vcs is imported and initialized.