Re: [Matplotlib-users] Plotting data from serial stream

[Brian Z. <br...@gm...>]

I've done this successfully with both the Qt4 and WX Agg backends.  The part
you care about is the update method.

Here's the snippet I use for Qt.  It shouldn't change except for your
imports at the top if you're using Wx.  Note, I've trimmed this down a bit,
so hopefully I didn't trim out anything important:


from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as
FigureCanvas

class PlotWidget(QWidget):

    def __init__(self, parent):
        QWidget.__init__(self, parent)

        self.dpi=72
        self.figure = Figure(dpi=self.dpi, linewidth=3)

        self.canvas = FigureCanvas(self.figure)
        self.canvas.setParent(self)

        self.ax = self.figure.add_subplot(111)

        (self.__times, self.__temps) = ([], [])
        self.background = self.canvas.copy_from_bbox(self.ax.bbox)
        self.plotting_line = self.ax.plot([], color='red', lw=2)[0]

    def update(self, temp, secs):
        try:
            self.__times.append(secs)
            self.__temps.append(temp)

            self.canvas.restore_region(self.background)

            self.plotting_line.set_xdata(self.__times)
            self.plotting_line.set_ydata(self.__temps)

            self.ax.draw_artist(self.plotting_line)
            self.canvas.blit(self.ax.bbox)
        except IndexError:
            pass

        self.canvas.draw()



On Fri, Mar 12, 2010 at 12:36 PM, Gökhan Sever <gok...@gm...>wrote:

> Hello,
>
> I read a simple data stream from my computers serial port. I can nicely
> read the data using pyserial library but couldn't get it *nicely* working
> neither with WXAgg nor Qt4Agg using the following code. Although with WX I
> could get updated looks, the figure isn't very responsive in this way. I
> have looked at simple_idle_wx example but for some reason I can't make it
> work to update the canvas whenever the condition satisfied.
>
> What is the trick to make the real-time data plotted on the screen easily
> without blocking the figure itself?
>
> import serial
> import matplotlib.pyplot as plt
> plt.ion()
>
> ser = serial.Serial(0)
>
> conc = []
> while True:
>     s = ser.readline()
>     if s.startswith('CONC'):
>         conc.append(float(s.split()[2]))
>         plt.plot(conc)
>         plt.show()
>         plt.clf()
>
> ser.close()
>
> --
> Gökhan
>
>
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