You are reading documentation for the unreleased version of Matplotlib. Try searching for the released version of this page instead?
Applications are open for the 2018 John Hunter Matplotlib Summer Fellowship. Apply now!
Version 2.2.2.post1752+g4b1f956cb
matplotlib
Fork me on GitHub

Related Topics

Fourier Demo WXΒΆ

import numpy as np

import wx
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.figure import Figure


class Knob(object):
    """
    Knob - simple class with a "setKnob" method.
    A Knob instance is attached to a Param instance, e.g., param.attach(knob)
    Base class is for documentation purposes.
    """

    def setKnob(self, value):
        pass


class Param(object):
    """
    The idea of the "Param" class is that some parameter in the GUI may have
    several knobs that both control it and reflect the parameter's state, e.g.
    a slider, text, and dragging can all change the value of the frequency in
    the waveform of this example.
    The class allows a cleaner way to update/"feedback" to the other knobs when
    one is being changed.  Also, this class handles min/max constraints for all
    the knobs.
    Idea - knob list - in "set" method, knob object is passed as well
      - the other knobs in the knob list have a "set" method which gets
        called for the others.
    """

    def __init__(self, initialValue=None, minimum=0., maximum=1.):
        self.minimum = minimum
        self.maximum = maximum
        if initialValue != self.constrain(initialValue):
            raise ValueError('illegal initial value')
        self.value = initialValue
        self.knobs = []

    def attach(self, knob):
        self.knobs += [knob]

    def set(self, value, knob=None):
        self.value = value
        self.value = self.constrain(value)
        for feedbackKnob in self.knobs:
            if feedbackKnob != knob:
                feedbackKnob.setKnob(self.value)
        return self.value

    def constrain(self, value):
        if value <= self.minimum:
            value = self.minimum
        if value >= self.maximum:
            value = self.maximum
        return value


class SliderGroup(Knob):
    def __init__(self, parent, label, param):
        self.sliderLabel = wx.StaticText(parent, label=label)
        self.sliderText = wx.TextCtrl(parent, -1, style=wx.TE_PROCESS_ENTER)
        self.slider = wx.Slider(parent, -1)
        # self.slider.SetMax(param.maximum*1000)
        self.slider.SetRange(0, param.maximum * 1000)
        self.setKnob(param.value)

        sizer = wx.BoxSizer(wx.HORIZONTAL)
        sizer.Add(self.sliderLabel, 0,
                  wx.EXPAND | wx.ALIGN_CENTER | wx.ALL,
                  border=2)
        sizer.Add(self.sliderText, 0,
                  wx.EXPAND | wx.ALIGN_CENTER | wx.ALL,
                  border=2)
        sizer.Add(self.slider, 1, wx.EXPAND)
        self.sizer = sizer

        self.slider.Bind(wx.EVT_SLIDER, self.sliderHandler)
        self.sliderText.Bind(wx.EVT_TEXT_ENTER, self.sliderTextHandler)

        self.param = param
        self.param.attach(self)

    def sliderHandler(self, evt):
        value = evt.GetInt() / 1000.
        self.param.set(value)

    def sliderTextHandler(self, evt):
        value = float(self.sliderText.GetValue())
        self.param.set(value)

    def setKnob(self, value):
        self.sliderText.SetValue('%g' % value)
        self.slider.SetValue(value * 1000)


class FourierDemoFrame(wx.Frame):
    def __init__(self, *args, **kwargs):
        wx.Frame.__init__(self, *args, **kwargs)
        panel = wx.Panel(self)

        # create the GUI elements
        self.createCanvas(panel)
        self.createSliders(panel)

        # place them in a sizer for the Layout
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.canvas, 1, wx.EXPAND)
        sizer.Add(self.frequencySliderGroup.sizer, 0,
                  wx.EXPAND | wx.ALIGN_CENTER | wx.ALL, border=5)
        sizer.Add(self.amplitudeSliderGroup.sizer, 0,
                  wx.EXPAND | wx.ALIGN_CENTER | wx.ALL, border=5)
        panel.SetSizer(sizer)

    def createCanvas(self, parent):
        self.lines = []
        self.figure = Figure()
        self.canvas = FigureCanvas(parent, -1, self.figure)
        self.canvas.callbacks.connect('button_press_event', self.mouseDown)
        self.canvas.callbacks.connect('motion_notify_event', self.mouseMotion)
        self.canvas.callbacks.connect('button_release_event', self.mouseUp)
        self.state = ''
        self.mouseInfo = (None, None, None, None)
        self.f0 = Param(2., minimum=0., maximum=6.)
        self.A = Param(1., minimum=0.01, maximum=2.)
        self.createPlots()

        # Not sure I like having two params attached to the same Knob,
        # but that is what we have here... it works but feels kludgy -
        # although maybe it's not too bad since the knob changes both params
        # at the same time (both f0 and A are affected during a drag)
        self.f0.attach(self)
        self.A.attach(self)

    def createSliders(self, panel):
        self.frequencySliderGroup = SliderGroup(
            panel,
            label='Frequency f0:',
            param=self.f0)
        self.amplitudeSliderGroup = SliderGroup(panel, label=' Amplitude a:',
                                                param=self.A)

    def mouseDown(self, evt):
        if self.lines[0].contains(evt)[0]:
            self.state = 'frequency'
        elif self.lines[1].contains(evt)[0]:
            self.state = 'time'
        else:
            self.state = ''
        self.mouseInfo = (evt.xdata, evt.ydata,
                          max(self.f0.value, .1),
                          self.A.value)

    def mouseMotion(self, evt):
        if self.state == '':
            return
        x, y = evt.xdata, evt.ydata
        if x is None:  # outside the axes
            return
        x0, y0, f0Init, AInit = self.mouseInfo
        self.A.set(AInit + (AInit * (y - y0) / y0), self)
        if self.state == 'frequency':
            self.f0.set(f0Init + (f0Init * (x - x0) / x0))
        elif self.state == 'time':
            if (x - x0) / x0 != -1.:
                self.f0.set(1. / (1. / f0Init + (1. / f0Init * (x - x0) / x0)))

    def mouseUp(self, evt):
        self.state = ''

    def createPlots(self):
        # This method creates the subplots, waveforms and labels.
        # Later, when the waveforms or sliders are dragged, only the
        # waveform data will be updated (not here, but below in setKnob).
        self.subplot1, self.subplot2 = self.figure.subplots(2)
        x1, y1, x2, y2 = self.compute(self.f0.value, self.A.value)
        color = (1., 0., 0.)
        self.lines += self.subplot1.plot(x1, y1, color=color, linewidth=2)
        self.lines += self.subplot2.plot(x2, y2, color=color, linewidth=2)
        # Set some plot attributes
        self.subplot1.set_title(
            "Click and drag waveforms to change frequency and amplitude",
            fontsize=12)
        self.subplot1.set_ylabel("Frequency Domain Waveform X(f)", fontsize=8)
        self.subplot1.set_xlabel("frequency f", fontsize=8)
        self.subplot2.set_ylabel("Time Domain Waveform x(t)", fontsize=8)
        self.subplot2.set_xlabel("time t", fontsize=8)
        self.subplot1.set_xlim([-6, 6])
        self.subplot1.set_ylim([0, 1])
        self.subplot2.set_xlim([-2, 2])
        self.subplot2.set_ylim([-2, 2])
        self.subplot1.text(0.05, .95,
                           r'$X(f) = \mathcal{F}\{x(t)\}$',
                           verticalalignment='top',
                           transform=self.subplot1.transAxes)
        self.subplot2.text(0.05, .95,
                           r'$x(t) = a \cdot \cos(2\pi f_0 t) e^{-\pi t^2}$',
                           verticalalignment='top',
                           transform=self.subplot2.transAxes)

    def compute(self, f0, A):
        f = np.arange(-6., 6., 0.02)
        t = np.arange(-2., 2., 0.01)
        x = A * np.cos(2 * np.pi * f0 * t) * np.exp(-np.pi * t ** 2)
        X = A / 2 * \
            (np.exp(-np.pi * (f - f0) ** 2) + np.exp(-np.pi * (f + f0) ** 2))
        return f, X, t, x

    def setKnob(self, value):
        # Note, we ignore value arg here and just go by state of the params
        x1, y1, x2, y2 = self.compute(self.f0.value, self.A.value)
        # update the data of the two waveforms
        self.lines[0].set(xdata=x1, ydata=y1)
        self.lines[1].set(xdata=x2, ydata=y2)
        # make the canvas draw its contents again with the new data
        self.canvas.draw()


class App(wx.App):
    def OnInit(self):
        self.frame1 = FourierDemoFrame(parent=None, title="Fourier Demo",
                                       size=(640, 480))
        self.frame1.Show()
        return True

app = App()
app.MainLoop()

Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery