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| 1 | +#!/usr/bin/env python |
| 2 | +""" |
| 3 | +Edward Tufte uses this example from Anscombe to show 4 datasets of x |
| 4 | +and y that have the same mean, standard deviation, and regression |
| 5 | +line, but which are qualitatively different. |
| 6 | +
|
| 7 | +matplotlib fun for a rainy day |
| 8 | +""" |
| 9 | + |
| 10 | +from matplotlib.matlab import * |
| 11 | + |
| 12 | +x = array([10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5]) |
| 13 | +y1 = array([8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68]) |
| 14 | +y2 = array([9.14, 8.14, 8.74, 8.77, 9.26, 8.10, 6.13, 3.10, 9.13, 7.26, 4.74]) |
| 15 | +y3 = array([7.46, 6.77, 12.74, 7.11, 7.81, 8.84, 6.08, 5.39, 8.15, 6.42, 5.73]) |
| 16 | +x4 = array([8,8,8,8,8,8,8,19,8,8,8]) |
| 17 | +y4 = array([6.58,5.76,7.71,8.84,8.47,7.04,5.25,12.50,5.56,7.91,6.89]) |
| 18 | + |
| 19 | +def fit(x): |
| 20 | + return 3+0.5*x |
| 21 | + |
| 22 | + |
| 23 | + |
| 24 | +xfit = array( [min(x), max(x) ] ) |
| 25 | + |
| 26 | +subplot(221) |
| 27 | +plot(x,y1,'ks', xfit, fit(xfit), 'r-', lw=2) |
| 28 | +axis([2,20,2,14]) |
| 29 | +set(gca(), xticklabels=[], yticks=(4,8,12), xticks=(0,10,20)) |
| 30 | +text(3,12, 'I', fontsize=20) |
| 31 | + |
| 32 | +subplot(222) |
| 33 | +plot(x,y2,'ks', xfit, fit(xfit), 'r-', lw=2) |
| 34 | +axis([2,20,2,14]) |
| 35 | +set(gca(), xticklabels=[], yticks=(4,8,12), yticklabels=[], xticks=(0,10,20)) |
| 36 | +text(3,12, 'II', fontsize=20) |
| 37 | + |
| 38 | +subplot(223) |
| 39 | +plot(x,y3,'ks', xfit, fit(xfit), 'r-', lw=2) |
| 40 | +axis([2,20,2,14]) |
| 41 | +text(3,12, 'IIII', fontsize=20) |
| 42 | +set(gca(), yticks=(4,8,12), xticks=(0,10,20)) |
| 43 | + |
| 44 | +subplot(224) |
| 45 | + |
| 46 | +xfit = array([min(x4),max(x4)]) |
| 47 | +plot(x4,y4,'ks', xfit, fit(xfit), 'r-', lw=2) |
| 48 | +axis([2,20,2,14]) |
| 49 | +set(gca(), yticklabels=[], yticks=(4,8,12), xticks=(0,10,20)) |
| 50 | +text(3,12, 'IV', fontsize=20) |
| 51 | + |
| 52 | +#verify the stats |
| 53 | +pairs = (x,y1), (x,y2), (x,y3), (x4,y4) |
| 54 | +for x,y in pairs: |
| 55 | + print 'mean=%1.2f, std=%1.2f, r=%1.2f'%(mean(y), std(y), corrcoef(x,y)[0][1]) |
| 56 | + |
| 57 | +show() |
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