Re: [Matplotlib-users] update an existing contour plot with new data
On Fri, Jul 9, 2010 at 6:28 AM, Johannes Röhrs johanne...@met.no wrote: I have some troubles updating a contour plot. I reduced my code to a simple example to reproduce the problem: [code] from pylab * import scipy as sp x=sp.arange(0,2*sp.pi,0.1) X,Y=sp.meshgrid(x,x) f1=sp.sin(X)+sp.sin(Y) f2=sp.cos(X)+sp.cos(Y) figure() C=contourf(f1) show() C.set_array(f2) draw() [\code] What do I need to do to update an existing contour plot with new data? The set_array() method (I think) only impacts the colormapping information for contourf, and even then doesn't appear to update. What you need to do is make a new contour plot and remove the old one, especially if you need to change the underlying contoured data. This should be as easy as C.remove(), but for some reason, this doesn't exist (I'll go add it in a minute). So instead, you need to do the following: import matplotlib.pyplot as plt import numpy as np x = np.arange(0, 2 * np.pi, 0.1) X,Y = np.meshgrid(x,x) f1 = np.sin(X) + np.sin(Y) f2 = np.cos(X) + np.cos(Y) plt.figure() C = plt.contourf(f1) plt.show() for coll in C.collections: plt.gca().collections.remove(coll) C = plt.contourf(f2) plt.draw() Ryan -- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma -- This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] update an existing contour plot with new data
Thanks a lot, this solutions seems to serve my purpose. A new method C.remove() would of course be even better. One could say the problem is solved, but why does there no method exist to update a contour plot as there is for many other plot routines, i.e. set_xdata/set_ydata for plot set_data for imshow or set_UVC for quiver and so on. set_array should be the corresponding method for contour plots, and if type C.get_array() I actually get the data array that I used to plot the countours! My purpose of this is to animate the contour plot, and I did read somewhere that updating the plot is much faster/more efficient than deleting and recreating the plot. - Original Message - From: Ryan May rma...@gmail.com To: Johannes Röhrs johanne...@met.no Cc: matplotlib-users@lists.sourceforge.net Sent: Friday, 9 July, 2010 5:11:37 PM Subject: Re: [Matplotlib-users] update an existing contour plot with new data On Fri, Jul 9, 2010 at 6:28 AM, Johannes Röhrs johanne...@met.no wrote: I have some troubles updating a contour plot. I reduced my code to a simple example to reproduce the problem: [code] from pylab * import scipy as sp x=sp.arange(0,2*sp.pi,0.1) X,Y=sp.meshgrid(x,x) f1=sp.sin(X)+sp.sin(Y) f2=sp.cos(X)+sp.cos(Y) figure() C=contourf(f1) show() C.set_array(f2) draw() [\code] What do I need to do to update an existing contour plot with new data? The set_array() method (I think) only impacts the colormapping information for contourf, and even then doesn't appear to update. What you need to do is make a new contour plot and remove the old one, especially if you need to change the underlying contoured data. This should be as easy as C.remove(), but for some reason, this doesn't exist (I'll go add it in a minute). So instead, you need to do the following: import matplotlib.pyplot as plt import numpy as np x = np.arange(0, 2 * np.pi, 0.1) X,Y = np.meshgrid(x,x) f1 = np.sin(X) + np.sin(Y) f2 = np.cos(X) + np.cos(Y) plt.figure() C = plt.contourf(f1) plt.show() for coll in C.collections: plt.gca().collections.remove(coll) C = plt.contourf(f2) plt.draw() Ryan -- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma -- This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] update an existing contour plot with new data
On Fri, Jul 9, 2010 at 10:49 AM, Johannes Röhrs johanne...@met.no wrote: Thanks a lot, this solutions seems to serve my purpose. A new method C.remove() would of course be even better. One could say the problem is solved, but why does there no method exist to update a contour plot as there is for many other plot routines, i.e. set_xdata/set_ydata for plot set_data for imshow or set_UVC for quiver and so on. set_array should be the corresponding method for contour plots, and if type C.get_array() I actually get the data array that I used to plot the countours! My purpose of this is to animate the contour plot, and I did read somewhere that updating the plot is much faster/more efficient than deleting and recreating the plot. This is the case when setting up the initial book-keeping is a significant portion of the time to make the plot. In this case, most of the work is in generating the contours, so I don't think you'd get much savings. (Granted, I haven't tried to verify these assumptions.) Ryan -- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma -- This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
