Select nc variables for pygmt

Q&A PyGMT Q&A
1

Hi,all
I need to plot nc formatted grid files which contain some different variables. How to select the one I needed to plot using grdimage?
I tried the ncfilename?var, but it did not work.

Lei

2

The ncfilename?var method should work. Could you post the output of gmt grdinfo ncfilename and gdalinfo ncfilename so we can look at the NetCDF metadata?

3

Thanks.

I got the reason now. The var should not set like:

fig.grdimage(grid=grid?var,projection="Cyl_stere/150/-20/15c", region="g")

Instead, it should be:

grid = 'ncfilename?var'
fig.grdimage(grid=grid,projection="Cyl_stere/150/-20/15c", region="g")
2 Likes
4

Yep, and just for future reference, the relevant GMT documentation page is at https://docs.generic-mapping-tools.org/6.2/cookbook/features.html#modifiers-for-coards-compliant-netcdf-files. The ncfilename?var syntax is for 2-D NetCDF files, but apparently you can do more complicated selections on 3-D and 4-D NetCDF files too using e.g. ncfilename?var[1] or ncfilename?var[1,2]. Might come in handy someday!