Jose Gómez-Dans wrote: > Hi, > I am starting to play with Basemap. I have some raster data in > longitude/latitude (WGS-84, EPSG: 4326). I would like to plot it using > imshow, and to then plot some country boundaries and so on and so forth. I > have studied the plotprecip.py example in Basemap's distribution, but as far > as i can tell, there's no reprojection of the data there (i.e., the data is > already in whatever projection Basemap was initiated with). While I can > reproject the data outside of MPL, I was wondering whether I'm missing > something, and I can just reproject my data and call imshow within my python > script. > > Cheers, > J > > > > Jose: If you data is on a lat/lon grid, you can plot it directly with Basemap with projection='cyl'. If you want to plot it on some other projection, you can reproject the data with Basemap quite easily. The test.py script in the examples directory shows how to reproject lat/lon data and plot with imshow for each of the map projections Basemap supports.
The basic recipe is this: import numpy as np import matplotlib.pyplot as plt # transform to nx x ny regularly spaced 40km native projection grid nx = int((m.xmax-m.xmin)/40000.)+1; ny = int((m.ymax-m.ymin)/40000.)+1 # datain is input data on lat/lon grid described by 1d arrays lons, lats # (longitudes and latitudes in degrees). topodat = m.transform_scalar(datain,lons,lats,nx,ny) # plot image over map with imshow. m is a Basemap instance defining the projection # you want to plot on. im = m.imshow(topodat,plt.cm.jet) Note that to plot the data with pcolor/pcolormesh of contourf, you don't need to interpolate to a native projection grid. You can just do lons, lats = np.meshgrid(lons,lats) x,y = m(lons,lats) im = m.pcolormesh(x,y,datain) -Jeff -- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/PSD R/PSD1 Email : [EMAIL PROTECTED] 325 Broadway Office : Skaggs Research Cntr 1D-113 Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
