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Polynomial explorer. You tell this module what order of polynomial you want and it will set up a figure with a graph of that polynomial plotted with x = -1 to +1. It will set up a second figure with a set of coefficient axes. You can click on the coeffiecient axes to set the coefficents. The graph will then update to reflect the values of the new coefficients.

This code illustrates the use of mouse interaction using matplotlib

Python, 101 lines
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101``` ```"""Polynomial explorer. You tell this module what order of polynomial you want and it will set up a figure with a graph of that polynomial plotted with x = -1 to +1. It will set up a second figure with a set of coefficient axes. You can click on the coeffiecient axes to set the coefficents. The graph will then update to reflect the values of the new coefficients""" import pylab as M def f(x,c): """Pass in x (a scalar or vector) and pass in c (a vector) and this function will compute f(x) = x**n + c(n-1)*x**(n-1) ... + c(1)*x + c(0)""" N = len(c) y = M.zeros(len(x)) for n in xrange(N): y += c[n]*x**n y += x**N return y def fstring(c): """Pass the coefficients and return a string corresponding to the ploynomial""" order = len(c) fx = "\$f(x) = x^%d" %(order) for n in xrange(order-1): nn = order - 1 - n fx += " + %1.3f x^%d" %(c[nn],nn) fx += " + %1.3f\$" %(c[0]) return fx class Explorer: def __init__(self, norder = 2): """Initializes the class when returning an instance. Pass it the polynomial order. It will set up two figure windows, one for the graph the other for the coefficent interface. It will then initialize the coefficients to zero and plot the (not so interesting) polynomial.""" self.order = norder self.c = M.zeros(self.order,'f') self.ax = [None]*(self.order-1)#M.zeros(self.order-1,'i') #Coefficent axes self.ffig = M.figure() #The first figure window has the plot self.replotf() self.cfig = M.figure() #The second figure window has the row = M.ceil(M.sqrt(self.order-1)) for n in xrange(self.order-1): self.ax[n] = M.subplot(row, row, n+1) M.setp(self.ax[n],'label', n) M.plot([0],[0],'.') M.axis([-1, 1, -1, 1]); self.replotc() M.connect('button_press_event', self.click_event) def replotf(self): """This replots the function given the coefficient array c.""" x = M.arange(-1,1.,.001) M.ioff() M.figure(self.ffig.number) M.cla() M.plot(x, f(x,self.c)) M.title(fstring(self.c)) M.draw() def replotc(self): """This replots the coefficients.""" M.figure(self.cfig.number) M.ioff() for n in xrange(self.order-1): M.axes(self.ax[n]) #M.cla() M.plot([self.c[n]], [self.c[n+1]],'ko') M.xlabel("\$c_%d\$" %(n)) M.ylabel("\$c_%d\$" %(n+1)) M.axis([-1, 1, -1, 1]); del self.ax[n].lines[0] M.draw() def click_event(self, event): """Whenever a click occurs on the coefficent axes we modify the coefficents and update the plot""" if event.xdata is None:#we clicked outside the axis return idx = M.getp(event.inaxes,'label') print idx, event.xdata, event.ydata self.c[idx] = event.xdata self.c[idx+1] = event.ydata self.replotf() self.replotc() ```
 Created by Kaushik Ghose on Thu, 11 Sep 2008 (MIT)