wxPython GUI: migrating gnuplot to matplotlib

Question

I currently have a GUI built in wxPython with several sections, one of which displays a .png image of a plot:

self.plot = wx.BitmapButton(self.pane_system, -1, wx.Bitmap("/home/myname/projects/newton/plot/src/graph.png", wx.BITMAP_TYPE_ANY))

In another part of the GUI, there is a place where I can edit parameters. The current setup is that When I change the parameters and press enter, the code tells Gnuplot to re-plot and save the new plot to the graph.png file, then update the GUI to show the updated image.

I have several general questions:

• I want to migrate gnuplot to matplotlib for the following reason: If I use gnuplot, the machine that is running the executable must have gnuplot installed on their machine. On the other hand, matplotlib is a python module, so I don't have to worry about installing graphical packages on the other machines. Is this assumption correct?

• How can I modify my wxPython GUI window to show the matplotlib plot? I found tutorials several telling me how to create a new panel with a matplotlib plot, but I would like to simply have it appear where the old plot was. I think I can make matplotlib save the plot to an image file just as I did in gnuplot. Is it generally a good idea to save the plot as an image and update the GUI, or are there other (faster) best practices for updating plots? One drawback of using image files (as in the above code) is that they do not resize when I resize the GUI window.

• If I package this as an executable, will I have to install wxPython/Python on a Windows machine to make the executable run?

Answer 1

Taking your questions in order:

1.) Yes matplotlib is a contained python module. It does have external dependancies but in Windows these dependencies are packaged with the matplotlib install. Do you need to worry about these when you install on other machines? That depends on how you are going to install. Are you packing to an exe? Having the end users install Python and matplotlib? As an example you can package matplotlib into your exe with py2exe, see here. Of course you'll have to customize those scripts for your backend, wx.

2.) You are seeing the panels with plots because matplotlib provides the FigureCanvasWxAgg, which is a wxWidget derived from wxPanel that plays nice with matplotlib. The advantages of using it are that you can set handlers for stuff like resize and painting.

Your wxBitMapButton, though is looking for a wxBitmap for the image. You might be able to give it a file handle (cStringIO.StringIO) to a matplotlib plot and eliminate the need to write a file to disk. You also could probably hook it's resize event and get matplotlib to redraw the figure to the appropriate size. You aren't going to have the amount of flexibility as using the FigureCanvasWxAgg. I can't research any of this, though, as it seems the wxPython web-site is down.

3.) You can package wxPython into executable. How depends on what packager you are using. I've done this with py2exe many times.