Real-time multiple data series

Question

I’m kind of new to Python and trying to create a graphing application for values ​​read through RS232 from a sensor. I managed (after some examples of reading and copying on the Internet) to get a plot working on a timer update that is great. My only problem is that I cannot get multiple rows of data into the same plot. Anyone have a solution?

This is the code that I have developed so far:

import os import pprint import random import sys import wx # The recommended way to use wx with mpl is with the WXAgg backend import matplotlib matplotlib.use('WXAgg') from matplotlib.figure import Figure from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigCanvas, NavigationToolbar2WxAgg as NavigationToolbar import numpy as np import pylab DATA_LENGTH = 100 REDRAW_TIMER_MS = 20 def getData(): return int(random.uniform(1000, 1020)) class GraphFrame(wx.Frame): # the main frame of the application def __init__(self): wx.Frame.__init__(self, None, -1, "Usart plotter", size=(800,600)) self.Centre() self.data = [] self.paused = False self.create_menu() self.create_status_bar() self.create_main_panel() self.redraw_timer = wx.Timer(self) self.Bind(wx.EVT_TIMER, self.on_redraw_timer, self.redraw_timer) self.redraw_timer.Start(REDRAW_TIMER_MS) def create_menu(self): self.menubar = wx.MenuBar() menu_file = wx.Menu() m_expt = menu_file.Append(-1, "&Save plot\tCtrl-S", "Save plot to file") self.Bind(wx.EVT_MENU, self.on_save_plot, m_expt) menu_file.AppendSeparator() m_exit = menu_file.Append(-1, "E&xit\tCtrl-X", "Exit") self.Bind(wx.EVT_MENU, self.on_exit, m_exit) self.menubar.Append(menu_file, "&File") self.SetMenuBar(self.menubar) def create_main_panel(self): self.panel = wx.Panel(self) self.init_plot() self.canvas = FigCanvas(self.panel, -1, self.fig) # pause button self.pause_button = wx.Button(self.panel, -1, "Pause") self.Bind(wx.EVT_BUTTON, self.on_pause_button, self.pause_button) self.Bind(wx.EVT_UPDATE_UI, self.on_update_pause_button, self.pause_button) self.hbox1 = wx.BoxSizer(wx.HORIZONTAL) self.hbox1.Add(self.pause_button, border=5, flag=wx.ALL | wx.ALIGN_CENTER_VERTICAL) self.vbox = wx.BoxSizer(wx.VERTICAL) self.vbox.Add(self.canvas, 1, flag=wx.LEFT | wx.TOP | wx.GROW) self.vbox.Add(self.hbox1, 0, flag=wx.ALIGN_LEFT | wx.TOP) self.panel.SetSizer(self.vbox) #self.vbox.Fit(self) def create_status_bar(self): self.statusbar = self.CreateStatusBar() def init_plot(self): self.dpi = 100 self.fig = Figure((3.0, 3.0), dpi=self.dpi) self.axes = self.fig.add_subplot(111) self.axes.set_axis_bgcolor('white') self.axes.set_title('Usart data', size=12) pylab.setp(self.axes.get_xticklabels(), fontsize=8) pylab.setp(self.axes.get_yticklabels(), fontsize=8) # plot the data as a line series, and save the reference # to the plotted line series # self.plot_data = self.axes.plot( self.data, linewidth=1, color="blue", )[0] def draw_plot(self): # redraws the plot xmax = len(self.data) if len(self.data) > DATA_LENGTH else DATA_LENGTH xmin = xmax - DATA_LENGTH ymin = 0 ymax = 4096 self.axes.set_xbound(lower=xmin, upper=xmax) self.axes.set_ybound(lower=ymin, upper=ymax) # enable grid #self.axes.grid(True, color='gray') # Using setp here is convenient, because get_xticklabels # returns a list over which one needs to explicitly # iterate, and setp already handles this. # pylab.setp(self.axes.get_xticklabels(), visible=True) self.plot_data.set_xdata(np.arange(len(self.data))) self.plot_data.set_ydata(np.array(self.data)) self.canvas.draw() def on_pause_button(self, event): self.paused = not self.paused def on_update_pause_button(self, event): label = "Resume" if self.paused else "Pause" self.pause_button.SetLabel(label) def on_save_plot(self, event): file_choices = "PNG (*.png)|*.png" dlg = wx.FileDialog( self, message="Save plot as...", defaultDir=os.getcwd(), defaultFile="plot.png", wildcard=file_choices, style=wx.SAVE) if dlg.ShowModal() == wx.ID_OK: path = dlg.GetPath() self.canvas.print_figure(path, dpi=self.dpi) self.flash_status_message("Saved to %s" % path) def on_redraw_timer(self, event): if not self.paused: newData = getData() self.data.append(newData) self.draw_plot() def on_exit(self, event): self.Destroy() def flash_status_message(self, msg, flash_len_ms=1500): self.statusbar.SetStatusText(msg) self.timeroff = wx.Timer(self) self.Bind( wx.EVT_TIMER, self.on_flash_status_off, self.timeroff) self.timeroff.Start(flash_len_ms, oneShot=True) def on_flash_status_off(self, event): self.statusbar.SetStatusText('') if __name__ == '__main__': app = wx.PySimpleApp() app.frame = GraphFrame() app.frame.Show() app.MainLoop() 

Answer 1

I decided, realizing that Plot () returned a list of strings.

Answer 2

Here is an example of matplotlib. It was originally written that to use a module that will receive analog data from arduino running firmata, but you should be able to get the corresponding bits from it: http://github.com/jsnyder/jbsnyder_tools/blob/master/plotanalog.py

I believe this may depend on the implementation of the ring buffer, as in this repo: http://github.com/jsnyder/jbsnyder_tools