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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):

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:
        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)

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

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

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

    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

        # 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)

    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.)

        # 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)

    def createSliders(self, panel):
        self.frequencySliderGroup = SliderGroup(
            label='Frequency f0:',
        self.amplitudeSliderGroup = SliderGroup(panel, label=' Amplitude 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'
            self.state = ''
        self.mouseInfo = (evt.xdata, evt.ydata,
                          max(self.f0.value, .1),

    def mouseMotion(self, evt):
        if self.state == '':
        x, y = evt.xdata, evt.ydata
        if x is None:  # outside the axes
        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).
        if not hasattr(self, 'subplot1'):
            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
            "Click and drag waveforms to change frequency and amplitude",
        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'$X(f) = \mathcal{F}\{x(t)\}$',
        self.subplot2.text(0.05, .95,
                           r'$x(t) = a \cdot \cos(2\pi f_0 t) e^{-\pi t^2}$',

    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

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

app = App()

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