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POimshow and histogram2d: can't get them to work
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  1. POimshow and histogram2d: can't get them to work
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    copied!<p>I'm learning Python and this is my first question here. I've read other topics related to the usage of <strong>imshow</strong> but didn't find anything useful. Sorry for my bad English.</p> <p>I have plotted a set of points here, left graphic:</p> <p><a href="https://dl.dropbox.com/u/10411539/python/image.png" rel="noreferrer">points (left) and image (right)</a></p> <p>Now I'd like to see an image of the density of points, so I used <strong>imshow</strong> and <strong>histogram2d</strong>, and I got the image to the right in the previous link.</p> <p>The image doesn't correspond to the distribution of points. How is this possible? I've followed the instructions in the help and even changed some parameters but nothing worked :( </p> <p>The code is:</p> <pre><code>import numpy as np import matplotlib.pyplot as plt import matplotlib.cm as cm j, h, k = np.loadtxt("test.dat", usecols=(2, 4, 6), \ unpack=True) # límites xmin = -0.5 xmax = 3.0 ymin = -0.5 ymax = 4.0 # colores j_h = j - h h_k = h - k # no todas las estrellas son graficadas x1 = 0.5 y1 = 0.5 b = 2.2 c = y1 - b * x1 x = y = np.array([]) for xi, yi in zip(h_k, j_h): if xi &lt; (yi - c) / b: x = np.append(x, xi) y = np.append(y, yi) # gráfico fig = plt.figure(figsize=(8, 7)) ax = fig.add_subplot(111) #ax.plot(x, y, "go") ax.set_xlabel(r"X", fontsize=14) ax.set_ylabel(r"Y", fontsize=14) ax.axis([xmin, xmax, ymin, ymax]) # imagen rango = [[xmin, xmax], [ymin, ymax]] binsx = int((xmax - xmin) / 0.05) binsy = int((ymax - ymin) / 0.05) binsxy = [binsx, binsy] H, xedges, yedges = np.histogram2d(x, y, range=rango, bins=binsxy) extent = [yedges[0], yedges[-1], xedges[0], xedges[-1]] cp = ax.imshow(H, interpolation='bilinear', extent=extent, cmap=cm.jet) fig.colorbar(cp) plt.show() </code></pre> <p>The links for the data used is here:</p> <p><a href="https://dl.dropbox.com/u/10411539/python/test.dat" rel="noreferrer">https://dl.dropbox.com/u/10411539/python/test.dat</a></p> <p>Any help is appreciated!</p>
 

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