Tim Michelsen wrote: > Dear Matplotlib-Users, > I am tryring to create a contour plot over a basemap. > > My main problem is creating the array for the Z values as a basis for the > plt.contour command from a CSV file where latitude, longitude and value are > stored column-wise: > > lat; lon; value > 50; 10; 6 > ... > > The data represents a regular spaced grid with a datapoint each 0.25 degrees. > > I tried various possibilities but didn't have success: > > 1) following simpletest.py from the basemap examples: > X, Y = meshgrid(data[:,1], data[:,0]) > > Z = data[:,2] > Timmie: Try:
X, Y = meshgrid(data[:,1], data[:,0]) Z = data[:,2] nlons = X.shape[1]; nlats = X.shape[0] Z = Z.reshape(nlats,nlons) > m.contourf(x,y, Z) > > => Error: Z must be a 2D array > -> How do I get Z to be a 2D array? > > 2) using the griddata package > Here I was nearly without orientation how to call griddata correctly. > You don't need to use griddata since you have regularly gridded data. > > 3) Using the python bindings of ogr > Any examples on this one? > Again, no need. A simple reshape will get you the 2d lat/lon array you need. > >From my above demonstrated methods the following questions arrise: > What is the preferred way to plot > - Points stored in the above descripbed format (lat, lon, value)? > - Interpolate a grid of data points by using different interpolation > methods > like inverse distance wheighting, natural neighbor interpolation, etc. to > get a > contour map? > For interpolation of irregular, randomly distributed data points see http://www.scipy.org/Cookbook/Matplotlib/Gridding_irregularly_spaced_data. However, if there is some structure to the data grid then it's probably better not to use these approaches. -Jeff -- Jeffrey S. Whitaker Phone : (303)497-6313 NOAA/OAR/CDC R/PSD1 FAX : (303)497-6449 325 Broadway Boulder, CO, USA 80305-3328 ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
