In [1]:
import numpy as np
import math, time
import Ngl,Nio
Retrieve time for wallclock time computation.
In [2]:
t1 = time.time() #-- retrieve start time
print ""
Open and read variable and grid.
In [3]:
#-- define variables
diri = "/Users/k204045/NCL/PyNGL/User_Guide_examples/" #-- data path
fname = "ta_ps_850.nc" #-- data file
gname = "r2b4_amip.nc" #-- grid info file
#-- open file and read variables
f = Nio.open_file(diri + fname,"r") #-- add data file
g = Nio.open_file(diri + gname,"r") #-- add grid file (not contained in data file!!!)
#-- read a timestep of "ta"
var = f.variables["ta"][0,0,:] #-- first time step, lev, ncells
print "-----------------------"
print f.variables["ta"] #-- like printVarSummary
print "-----------------------"
Define title string, minimum and maximum contour values, interval and levels.
In [4]:
title = "ICON: Surface temperature" #-- title string
varMin = 230 #-- data minimum
varMax = 310 #-- data maximum
varInt = 5 #-- data increment
levels = range(varMin,varMax,varInt) #-- set levels array
Define the x-, y-values and the polygon points.
In [5]:
rad2deg = 45./np.arctan(1.) #-- radians to degrees
x = g.variables["clon"][:] #-- read clon
y = g.variables["clat"][:] #-- read clat
vlon = g.variables["clon_vertices"][:] #-- read clon_vertices
vlat = g.variables["clat_vertices"][:] #-- read clat_vertices
ncells = vlon.shape[0] #-- number of cells
nv = vlon.shape[1] #-- number of edges
x = x * rad2deg #-- cell center, lon
y = y * rad2deg #-- cell center, lat
vlat = vlat * rad2deg #-- cell lattitude vertices
vlon = vlon * rad2deg #-- cell longitude vertices
#-- longitude values -180. - 180.
for j in range(1,ncells):
for i in range(1,nv):
if vlon[j,i] < -180. :
vlon[j,i] = vlon[j,i] + 360.
if vlon[j,i] > 180. :
vlon[j,i] = vlon[j,i] - 360.
#-- print some information
print ""
print "Cell points: ", nv
print "Cells: ", str(ncells)
print "Variable ta min/max: %.2f " % np.min(var) + "/" + " %.2f" % np.max(var)
print ""
Open a workstation, here x11 window.
In [6]:
#-- open a workstation
wks_type = "png" #-- graphics output type
wks = Ngl.open_wks(wks_type,"plot_contour_unstructured_PyNGL") #-- open a workstation
Set resources.
In [7]:
res = Ngl.Resources() #-- plot mods desired.
res.cnFillOn = True #-- color plot desired
res.cnFillMode = "CellFill" #-- set fill mode
res.cnFillPalette = "BlueWhiteOrangeRed" #-- choose colormap
res.cnLinesOn = False #-- turn off contour lines
res.cnLineLabelsOn = False #-- turn off contour labels
res.cnLevelSelectionMode = "ExplicitLevels" #-- use explicit levels
res.cnLevels = levels #-- set levels
res.lbOrientation = "Horizontal" #-- vertical by default
res.lbBoxLinesOn = False #-- turn off labelbar boxes
res.lbLabelFontHeightF = 0.01 #-- labelbar label font size
res.mpFillOn = False #-- don't use filled map
res.mpGridAndLimbOn = False #-- don't draw grid lines
res.sfXArray = x #-- transform x to mesh scalar field
res.sfYArray = y #-- transform y to mesh scalar field
res.sfXCellBounds = vlon #-- needed if set cnFillMode = "CellFill"
res.sfYCellBounds = vlat #-- needed if set cnFillMode = "CellFill"
res.tiMainString = "Unstructured grid: ICON" #-- title string
res.tiMainOffsetYF = 0.03 #-- move main title towards plot
Draw the plot.
In [8]:
#-- create the plot
plot = Ngl.contour_map(wks,var,res)
Compute the wallclock time
In [9]:
t2 = time.time()
print "Wallclock time: %0.3f seconds" % (t2-t1)
print ""
Ngl.delete_wks(wks) #-- this need to be done to close the graphics output file
Ngl.end()
Show the plot in this notebook.
In [10]:
from IPython.display import Image
Image(filename='plot_contour_unstructured_PyNGL.png')
Out[10]: