## Re: [Matplotlib-users] Plotting a list of lines

 Re: [Matplotlib-users] Plotting a list of lines From: Mauro Cavalcanti - 2008-11-27 17:21:28 ```Dear John, Thank you very much for your thoughtful reply. Indeed, the code fragment I sent was incomplete and not expected to do nothing else than illustrate the general idea (what, hopefully, it did). You suggested collections, and in my previous attempts I have already used them (worked quite well, but did not solved my problem). Perhaps my problem is a simpler than I am being able to see and it is (still) related to using MPL/Basemap embedded in a wx GUI. Well, in my previously presented sample application for plotting point-coordinate datasets (in that case, corresponding to cities) on a Basemap, I have checkboxes which I use to toggle the points on the map on and off. I do this by storing the plot corresponding to each dataset in a Python list, eg. self.plot_list.append(self.map.ax.plot(longs,lats,'o')) where map is a Basemap instance and longs,lats are float arrays of geographic coordinates in decimal format. Then, in a checkbox event, I do the following: index = event.GetSelection() plot = self.plot_list[index] if self.FileList.IsChecked(index): plot[0].set_visible(True) else: plot[0].set_visible(False) This works quite well and points are properly toggled on/off the Basemap. But then I want to plot minimum spanning trees connecting the point datasets. For this I do: n = len(nodes) for i in range(n): try: t = edges[i,0]-1 u = edges[i,1]-1 x = [nodes[t,0], nodes[u,0]] y = [nodes[t,1], nodes[u,1]] self.plot_list.append(map.ax.plot(x,y,'-b')) except: continue where nodes is the array of point coordinates and edges are the from/to indexes of the coordinates, computed with Prim's algorithm. The lines between points (representing the minimum spanning tree) are displayed OK. But then my problem appears: I cannot find a way to turn the entire tree (which is composed of n-1 line segments) on and off of the map in the same way I do with the points (as shown above). What I would like is to store all line segments inside the for loop, and then show the tree at once, outside the loop; so I could use the same "plot[0].set_visible(True|False)" I use for the points. Searching the list archives, I found that more than an year ago, another user, Mr. David Clark, had about the same problem (http://www.nabble.com/Toggle-plot-trace-tt8968338r0.html). Your answer to him helped me with toggling of the points, but not with the lines. Well, hope to have been as clear as possible. Thanks in advance for any assistance you can provide, and for your patience! With best regards, 2008/11/27 John Hunter : > > Could you be a little bit more clear about your use case? In the code > above, nothing is drawn inside the loop. The Line2D is created but not > rendered until a figure draw command is issued. So it would help to > know what it is that you are trying to achieve, rather than simply the > approach to the solution you are taking. -- Dr. Mauro J. Cavalcanti Ecoinformatics Studio P.O. Box 46521, CEP 20551-970 Rio de Janeiro, RJ, BRASIL E-mail: maurobio@... Web: http://studio.infobio.net Linux Registered User #473524 * Ubuntu User #22717 "Life is complex. It consists of real and imaginary parts." ```

 [Matplotlib-users] Plotting a list of lines From: Mauro Cavalcanti - 2008-11-27 13:29:53 ```Dear ALL, Is there a way to plot a list (a Python list) of lines (MPL Line2D objects) at once? For example, inside a loop I have: for i in range(n): line, = ax.plot(x,y) plot_list.append(line) In the code fragment above, "plot_list" is an ordinary Python list which will be filled with matplotlib.lines.Line2D objetcs, each of them representing a line in the plot. What I would like is how (if???) to plot this entire list of lines at once in a single plot, outside the for loop, but obviously this cannot be done with a canonical "plot" command. Thanks in advance. With regards, -- Dr. Mauro J. Cavalcanti Ecoinformatics Studio P.O. Box 46521, CEP 20551-970 Rio de Janeiro, RJ, BRASIL E-mail: maurobio@... Web: http://studio.infobio.net Linux Registered User #473524 * Ubuntu User #22717 "Life is complex. It consists of real and imaginary parts." ```
 Re: [Matplotlib-users] Plotting a list of lines From: Mauro Cavalcanti - 2008-11-27 17:21:28 ```Dear John, Thank you very much for your thoughtful reply. Indeed, the code fragment I sent was incomplete and not expected to do nothing else than illustrate the general idea (what, hopefully, it did). You suggested collections, and in my previous attempts I have already used them (worked quite well, but did not solved my problem). Perhaps my problem is a simpler than I am being able to see and it is (still) related to using MPL/Basemap embedded in a wx GUI. Well, in my previously presented sample application for plotting point-coordinate datasets (in that case, corresponding to cities) on a Basemap, I have checkboxes which I use to toggle the points on the map on and off. I do this by storing the plot corresponding to each dataset in a Python list, eg. self.plot_list.append(self.map.ax.plot(longs,lats,'o')) where map is a Basemap instance and longs,lats are float arrays of geographic coordinates in decimal format. Then, in a checkbox event, I do the following: index = event.GetSelection() plot = self.plot_list[index] if self.FileList.IsChecked(index): plot[0].set_visible(True) else: plot[0].set_visible(False) This works quite well and points are properly toggled on/off the Basemap. But then I want to plot minimum spanning trees connecting the point datasets. For this I do: n = len(nodes) for i in range(n): try: t = edges[i,0]-1 u = edges[i,1]-1 x = [nodes[t,0], nodes[u,0]] y = [nodes[t,1], nodes[u,1]] self.plot_list.append(map.ax.plot(x,y,'-b')) except: continue where nodes is the array of point coordinates and edges are the from/to indexes of the coordinates, computed with Prim's algorithm. The lines between points (representing the minimum spanning tree) are displayed OK. But then my problem appears: I cannot find a way to turn the entire tree (which is composed of n-1 line segments) on and off of the map in the same way I do with the points (as shown above). What I would like is to store all line segments inside the for loop, and then show the tree at once, outside the loop; so I could use the same "plot[0].set_visible(True|False)" I use for the points. Searching the list archives, I found that more than an year ago, another user, Mr. David Clark, had about the same problem (http://www.nabble.com/Toggle-plot-trace-tt8968338r0.html). Your answer to him helped me with toggling of the points, but not with the lines. Well, hope to have been as clear as possible. Thanks in advance for any assistance you can provide, and for your patience! With best regards, 2008/11/27 John Hunter : > > Could you be a little bit more clear about your use case? In the code > above, nothing is drawn inside the loop. The Line2D is created but not > rendered until a figure draw command is issued. So it would help to > know what it is that you are trying to achieve, rather than simply the > approach to the solution you are taking. -- Dr. Mauro J. Cavalcanti Ecoinformatics Studio P.O. Box 46521, CEP 20551-970 Rio de Janeiro, RJ, BRASIL E-mail: maurobio@... Web: http://studio.infobio.net Linux Registered User #473524 * Ubuntu User #22717 "Life is complex. It consists of real and imaginary parts." ```
 Re: [Matplotlib-users] Plotting a list of lines From: John Hunter - 2008-11-29 14:34:50 ```On Thu, Nov 27, 2008 at 11:21 AM, Mauro Cavalcanti wrote: > Then, in a checkbox event, I do the following: > > index = event.GetSelection() > plot = self.plot_list[index] > if self.FileList.IsChecked(index): > plot[0].set_visible(True) > else: > plot[0].set_visible(False) > > This works quite well and points are properly toggled on/off the Basemap. > > But then I want to plot minimum spanning trees connecting the point > datasets. For this I do: > > n = len(nodes) > for i in range(n): > try: > t = edges[i,0]-1 > u = edges[i,1]-1 > x = [nodes[t,0], nodes[u,0]] > y = [nodes[t,1], nodes[u,1]] > self.plot_list.append(map.ax.plot(x,y,'-b')) > except: > continue > > where nodes is the array of point coordinates and edges are the > from/to indexes of the coordinates, computed with Prim's algorithm. > The lines between points (representing the minimum spanning tree) are > displayed OK. But then my problem appears: I cannot find a way to turn > the entire tree (which is composed of n-1 line segments) on and off of > the map in the same way I do with the points (as shown above). What I > would like is to store all line segments inside the for loop, and then > show the tree at once, outside the loop; so I could use the same > "plot[0].set_visible(True|False)" I use for the points. Hi Mauro, Yes, you should be able to use a collection for this quite easily. One comment first. You never want to try/except and catch all exceptions w/o handling them in some way. If you want to catch a specific exception, fine, or of you want to catch all of them and log them and then reraise, also fine, but there is not good use case for catching them all and then continuing silently. Now, on to collections. In your example above, you would simply do:: segments = [] n = len(nodes) for i in range(n): t = edges[i,0]-1 u = edges[i,1]-1 xt, yt = nodes[t,0], nodes[t,1] # assuming xt, yt are scalars here.... xu, yu = nodes[u,0], nodes[u,1] segments.append( [ (xt,yt), (xu,yu) ] ) collection = collections.LineCollection(segments) and later:: collection.set_visible(True|False) # etc... Hope this helps, JDH ```