德国10马克纸币上的高斯：
图片来自：http://www.360doc.com/content/14/0906/11/2198695_407403312.shtml
python numpy.std():https://docs.scipy.org/doc/numpy/reference/generated/numpy.std.html
官方API上的一个例子：http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.hist
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""" Demo of the histogram (hist) function with a few features. In addition to the basic histogram, this demo shows a few optional features: * Setting the number of data bins * The ``normed`` flag, which normalizes bin heights so that the integral of the histogram is 1. The resulting histogram is a probability density. * Setting the face color of the bars * Setting the opacity (alpha value). """ import numpy as np import matplotlib.mlab as mlab import matplotlib.pyplot as plt # example data mu = 100 # mean of distribution sigma = 15 # standard deviation of distribution x = mu + sigma * np.random.randn(10000) num_bins = 50 # the histogram of the data n, bins, patches = plt.hist(x, num_bins, normed=1, facecolor='green', alpha=0.5) # add a 'best fit' line y = mlab.normpdf(bins, mu, sigma) plt.plot(bins, y, 'r--') plt.xlabel('Smarts') plt.ylabel('Probability') plt.title(r'Histogram of IQ: $\mu=100$, $\sigma=15$') # Tweak spacing to prevent clipping of ylabel plt.subplots_adjust(left=0.15) plt.show() |
结果：
