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-   -   Python program using netCDF help! (http://www.physicsforums.com/showthread.php?t=585926)

chapter Mar11-12 12:38 PM

Python program using netCDF help!
 
Hello, I need to write a program that will plot any set of .nc data with dimensions stored in t-z-y-x order but i'm having some problems thats driving me crazy.

first problem: how do I find the names of the variables for each dimension for example how would I find the name 'lat' for the latitude (I know in the .nc file but i'm not allowed to hard code it)

second problem: The graphs that I plot have white bits on the outside because the x and y axis are bigger than the data set, is there a way to eliminate this part?

my program is below notice that I have to hardcode the words 'lon' and 'lat when I need to get them from the file instead somehow!)


# Assignment2 module1
# FILENAME: A2P1

def plotMap(locStr, varStr, tI, zI):
'''reads a file location (string), variable (string), a time index and then a z index'''
print "importing..."
import numpy as np
import matplotlib
import netCDF4
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from netCDF4 import Dataset
import string

print "reading data..."
nc = Dataset(locStr)
var = nc.variables[varStr]

print "Converting the coordinates..."
lonvar = nc.variables['lon']
lonvals = lonvar[:]
latvar = nc.variables['lat']
latvals = latvar[:]

print "Creating plot attributes..."
data=var[zI]
pc=plt.pcolor(lonvals, latvals, data)
plt.colorbar(pc, orientation='horizontal')
plt.xlabel('longitude (' + lonvar.units +')')
plt.ylabel('latitude (' + latvar.units + ')')
plt.title('plot of ' + varStr + ' at level z=' + str(zI) + ' (' + var.units + ')')
ax=plt.gca()
ax.set_xlim(0,360)
ax.set_ylim(-90,90)

print "Plotting graph..."
plt.show()
plt.savefig(varStr + '.png')
return

import A2P1
A2P1.plotMap('/home/edev/classes/class7/FOAM_20110209.0.nc', 'TMP', 1, 12)
#A2P1.plotMap('/home/edev/classes/class6/GlobModel_temp.nc', 'Pressure', 1, 1)


here are links to two .nc file this program should work for but doesn't quite yet

http://ubuntuone.com/7lLwrQfbicWiOk613f3gkE
http://ubuntuone.com/5LcyOXP7YutIcc3UE6sD2X

I have used a lot of time looking for the command that will fix everything, your help will be very appretiated. If can't help and have a good idea of where to look that would be usedful too,

thank you

Jason


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