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DKRZ PyNGL example streamline plot

This example script shows how to plot streamlines.

Example:

from __future__ import print_function
import Ngl,Nio

#-- open a file and read variables
f    = Nio.open_file("rectilinear_grid_2D.nc", "r")

u    = f.variables["u10"]
v    = f.variables["v10"]
ua   = f.variables["u10"][0,:,:]
va   = f.variables["v10"][0,:,:]

lat  = f.variables["lat"]
lon  = f.variables["lon"]
nlon = len(lon)
nlat = len(lat)

#-- open a workstation
wks = Ngl.open_wks("png","plot_TRANS_streamline_py")

#-- resource settings
stres                  =  Ngl.Resources()
stres.nglFrame         =  False

stres.vfXArray         =  lon[::3]
stres.vfYArray         =  lat[::3]
 
stres.mpFillOn         =  True
stres.mpOceanFillColor = "Transparent"
stres.mpLandFillColor  = "Gray90"
stres.mpInlandWaterFillColor = "Gray90"

#-- create the plot, use every 3rd data value
plot = Ngl.streamline_map(wks,ua[::3,::3],va[::3,::3],stres)

#-- write variable long_name and units to the plot
txres               = Ngl.Resources()
txres.txFontHeightF = 0.014

Ngl.text_ndc(wks,f.variables["u10"].attributes['long_name'],0.16,0.76,txres)
Ngl.text_ndc(wks,f.variables["u10"].attributes['units'],    0.95,0.76,txres)

#-- advance the frame
Ngl.frame(wks)

Ngl.end()

Result:

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