Question

My program (developed with GTK using glade) receives some data and has the option to display a seperate window containing a matplotlib scatterplot that represents the data.

My problem is that if the user closes the graph window and reopens it, no graph is displayed. It is just a blank GTK Window. I’m sure there is a simple fix, but there aren’t many resources available that are relevant to my issue (or GTK and matlplotlib integration for that matter).

I have created a Module for my scatterplot so I can easily reuse it. I am just trying to get it to work, so the code isn’t structured perfectly.

##Scatterplot Module:

import gtk
import matplotlib
from matplotlib.backends.backend_gtkagg import FigureCanvasGTKAgg as FigureCanvas
from matplotlib.figure import Figure


class ScatterPlot:
    def __init__(self):
       self.window = gtk.Window()
       self.window.connect("destroy", lambda x: self.destroy())
       self.window.set_default_size(500,400)
       self.is_hidden = False

       self.figure = Figure(figsize = (5,4), dpi=100)
       self.ax = self.figure
       self.ax = self.ax.add_subplot(111)
       self.canvas = FigureCanvas(self.figure)
       self.window.add(self.canvas)

       self.Xs = list()
       self.Ys = list()

   def set_axis(self, xLimit = (0,384) , yLimit = (0,100)):
       self.ax.set_xlim(xLimit)
       self.ax.set_ylim(yLimit)

   def plot(self, xs, ys):
       self.Xs.extend([xs])
       self.Ys.extend([ys])
       self.ax.plot(xs,ys,'bo')

   def update(self):
       self.window.add(self.canvas)

   def set_title(self, title):
       self.ax.set_title(title)

   def show(self):
       self.window.show_all()
       self.is_hidden = False

   def hide(self):
       self.window.hide()
       self.is_hidden = True

   def destroy(self):
       self.window.destroy()

I call the module like so:

class GUI:
    def __init__(self):
        self.scatterplot = scatterplot.ScatterPlot()

        #When the user presses the "Graph" button it calls the following function
    def graph():
        self.scatterplot.plot(someDataX, someDataY)
        self.scatterplot.set_axis()
        self.scatterplot.set_title("Some Title")
        self.scatterplot.show()

(This was just an example of what my code looks like.)

When the scatterplot is closed, I am calling self.window.destroy instead of self.window.hide. When reopening is attempted, I call the same graph() function but, as stated above, the GTK Window does not display the graph. (When I first open it, it displays perfectly)

My speculations:

• Should I be calling .hide() instead of .destroy()?
• Is there a piece of code in scatterplot‘s constructor that needs to be called again to create the plot?
• Or should I just re-instantiate the plot every time graph() is called?

Answer 1

My Solution:

From:

class ScatterPlot:
    def __init__(self):
        #remove the following two lines
        self.canvas = FigureCanvas(self.figure)
        self.window.add(self.canvas)

Move the two lines of code to show()

def show(self):
    self.canvas = FigureCanvas(self.figure)
    self.window.add(self.canvas)
    self.window.show_all()
    self.is_hidden = False

Moving these two lines of code allows the graph to be displayed when re-opening the window.

Sidenote: Calling both .destroy() or .show() when closing the window will work. I’m not sure which one is better though.