Antoine De Pauw wrote: > Sir, > > I'm sorry, as english is not my mothertongue and it is sometimes difficult to > be understandable. > > All is in the script I gave to you initially, except the point drawing code > which would be useless as it is proven not to work (I dont know the method to > do it). > > What I have is a map, and a set of pixels I have to put on it with geographic > coordinates. > > I cannot find the right method to put colour pixels on the map, that's the > problem. > > I have that map in miller projection, and three arrays containing > respectively latitude, longitude and satellite measured value. > > What I need to obtain is something approximately like this: > http://www.oma.be/BIRA-IASB/Molecules/SO2archive/info/background/so2sc200703_00_lr.gif > but with the basemap toolkit. > > So, my question is: how could I do to plot a coloured pixel at coordinates > lat:lon on that map? If I have just the method to project a geographic > coordinate on the map and put a coloured pixel at the right place, all is > done and I just have to loop my arrays... Also, I would have to implement > some antialiasing on the map. > Antoine:
Are the pixels arranged on a regular grid - or are they randomly distributed? If they are on a grid, it's easy (using pcolor or imshow). If you could send me your data I may be able to get you started. (I'm cc'ing the matplotlib list so others can join in the discussion). -Jeff > If this is not possible to do it in a simple and explainable way, please tell > me and I'll continue using matlab or searching for the bit of code which will > save me > > Anyway, I have to thank you for your interest to help me.. > > Many thanks, > > Antoine De Pauw > > >> Antoine De Pauw wrote: >> >>> Hi, and thanks for the answer >>> >>> In fact, what I do is reading a binary file to obtain 3 arrays >>> (Lat,Lon,Val) describing geographic points which are associated by index >>> (like point 1 is Lat[0]:Lon[0] with value Val[0]) >>> >>> What I need to do is to plot some points on the map (miller projection for >>> most) based on latitude and longitude, to obtain a colour map (points are >>> unordered, it is from IASI satellite computations) >>> >>> I'm able to create a map, draw simple things on it, etc but the problem I >>> have is any method I try for plotting points is failing, either pcolor, >>> pcolormesh, imshow, etc. >>> >>> When I found your post on that mailing list, I figured out that you might >>> have the experience and skills to easily explain to me how to manipulate >>> these points and plot them on the map, as there's like no help on the web >>> except standard examples... >>> >>> Please tell me if this is possible for you to give me some tips, or if it >>> takes too much of your time just advice me some lectures >>> >>> Best regards, >>> >>> De Pauw Antoine >>> >>> >> Antoine: It would really help to have a script demonstrating your >> problem. It sounds to me like you want to plot markers representing a >> set of points - for that you should use the scatter method. pcolor, >> pcolormesh and friends are for plotting gridded data. >> >> -Jeff >> >>> >>> >>>> De Pauw Antoine wrote: >>>> >>>> >>>>> Dear sir, >>>>> >>>>> >>>>> >>>>> I’m currently trying to improve our plotting tools here at the >>>>> “Quantum >>>>> Chemistry and Photophysics” section of the Université Libre de >>>>> Bruxelles, and I ran, after many time passed at searching for a >>>>> solution, on an explanation from you here: >>>>> http://www.nabble.com/Re:-matplotlib-basemap-question-tt17759370.html >>>>> >>>>> >>>>> >>>>> It seems that you could help me find a solution, as I cannot plot any >>>>> points on maps. >>>>> >>>>> >>>>> >>>>> Could you please tell me what I could do to plot data in a simple way, >>>>> assuming I have 3 unordered arrays containing respectively latitude, >>>>> longitude and values to plot? >>>>> >>>>> >>>>> >>>>> Some tips would be very nice from you as any method I have tried so far >>>>> give me some errors… >>>>> >>>>> >>>>> >>>>> Thank you very much in advance, >>>>> >>>>> >>>>> >>>>> Best regards, >>>>> >>>>> >>>>> >>>>> PS: I give you the code I’m using currently, missing the plotting >>>>> part >>>>> >>>>> >>>>> >>>>> from mpl_toolkits.basemap import Basemap >>>>> >>>>> from numpy import * >>>>> >>>>> from scipy.io.numpyio import fread >>>>> >>>>> import matplotlib.pyplot as plt >>>>> >>>>> import numpy as np >>>>> >>>>> import os >>>>> >>>>> import sys >>>>> >>>>> import array >>>>> >>>>> >>>>> >>>>> fileName="c:/20080821.b56" >>>>> >>>>> >>>>> >>>>> print('preparing map') >>>>> >>>>> map = >>>>> Basemap(projection='mill',lat_0=0,lon_0=0,resolution='i',area_thresh=30000.) >>>>> >>>>> map.drawcoastlines(0.5,antialiased=1) >>>>> >>>>> map.drawmapboundary() >>>>> >>>>> #map.drawmeridians(np.arange(-180,180,60),linewidth=0.5, >>>>> labels=np.arange(-180,180,60), labelstyle="+/-") >>>>> >>>>> #map.drawparallels(np.arange(-90,90,30), linewidth=0.5, >>>>> labels=np.arange(-180,180,30), labelstyle="+/-") >>>>> >>>>> print('reading binary data') >>>>> >>>>> nbreligne=long(os.stat(fileName)[6])/(8*int(fileName[-2:])) >>>>> >>>>> Lat=zeros(nbreligne) >>>>> >>>>> Lon=zeros(nbreligne) >>>>> >>>>> Val=zeros(nbreligne) >>>>> >>>>> rawfile=fromfile(open(fileName,'rb'),'d',-1) >>>>> >>>>> Lat=rawfile[0:nbreligne] >>>>> >>>>> Lon=rawfile[nbreligne:nbreligne*2] >>>>> >>>>> Val=rawfile[nbreligne*21:nbreligne*22] >>>>> >>>>> print('shifting latitudes and projecting to map') >>>>> >>>>> i=0 >>>>> >>>>> while i < nbreligne: >>>>> >>>>> if(Lon[i]>180): >>>>> >>>>> print(Lon[i]) >>>>> >>>>> Lon[i]-=360 >>>>> >>>>> print(Lon[i]) >>>>> >>>>> i+=1 >>>>> >>>>> print('plotting data') >>>>> >>>>> >>>>> >>>>> #plotting code comes here >>>>> >>>>> >>>> Antoine: If you send me a self-contained script that produces the >>>> problem you see, I can help you debug it. As it stands now, I have very >>>> little to work with - it could be your plotting commands, or it could be >>>> your data. >>>> >>>> -Jeff >>>> >>>> >>>>> >>>>> >>>>> print('saving map') >>>>> >>>>> plt.savefig("testfig.png",dpi=600) >>>>> >>>>> print('done') >>>>> >>>>> >>>>> >>>>> *Antoine De Pauw* >>>>> Collaborateur de recherches, Informatique - Research collaborator, IT >>>>> Laboratoire de chimie quantique et photophysique - Quantum chemistry and >>>>> photophysics laboratory >>>>> *Université Libre de Bruxelles - ULB <http://ww.ulb.ac.be/>* >>>>> >>>>> >>>>> >>>>> >>>>> >>>> -- >>>> 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 >>>> >>>> >>>> >>>> >>> >>> >> -- >> Jeffrey S. Whitaker Phone : (303)497-6313 >> NOAA/OAR/CDC R/PSD1 FAX : (303)497-6449 >> 325 Broadway Boulder, CO, USA 80305-3328 >> >> >> >> > > > -- Jeffrey S. Whitaker Phone : (303)497-6313 NOAA/OAR/CDC R/PSD1 FAX : (303)497-6449 325 Broadway Boulder, CO, USA 80305-3328 ------------------------------------------------------------------------- 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
