[ncl-talk] advice for a scatter plot

[Will Hobbs]

Cathy

I use two ways of doing this; which is better depends a bit on how many ‘classifications’ you have. If you have just a few the first method is easier; for many classifications (e.g. different markers for each model in a multi-model ensemble) the 2nd method is better:


  1.  Make separate scatterplots for each classification (in your case time period) setting the xyMarkerColor resource each time, then use the overlay() function to merge them. You’ll need to explicitly ensure that your axis ranges include the full data set using trXMinF, trXMaxF, trYMinF and trYMaxF resources
  2.  Make a dummy base xy plot with the whole dataset, setting xyLineColor resource to “transparent” (if you want a 1-to-1 or regression fit line you can plot this line using dummy x and y arrays instead). Then add markers colored as required using gsn_add_polymarker()

That’s a bit of a brief, rushed overview – let me know if it’s not clear.

Will




From: ncl-talk <ncl-talk-bounces at ucar.edu> on behalf of Cathy Smith <cathy.smith at noaa.gov>
Date: Thursday, 21 February 2019 at 3:09 AM
To: "ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
Subject: [ncl-talk] advice for a scatter plot

NCLers

I would like to create a scatter plot of 2 time-series. That part is
easy in NCL :) But, I would like to color the markers as a function of
time. That is, if the time series were monthly from 1980-2010, then the
the dot for Jan 1980 pair of values might be blue while Dec 2010 would
transition to red. Is this possible? I see several NCL examples where
the color can be a function of the time-series values but not the itself.

Thanks for any advice.

Cathy

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