legend_auto.py

非原创。很好的python例子

"""
This file was written to test matplotlib's autolegend placement
algorithm, but shows lots of different ways to create legends so is
useful as a general examples

Thanks to John Gill and Phil ?? for help at the matplotlib sprint at
pycon 2005 where the auto-legend support was written.
"""
from pylab import *
import sys


N = 100
x = arange(N)

def fig_1():
    figure(1)
    t = arange(0, 40.0 * pi, 0.1)
    l, = plot(t, 100*sin(t), 'r', label='sine')
    legend(loc='best')

def fig_2():
    figure(2)
    plot(x, 'o', label='x=y')
    legend(loc='best')

def fig_3():
    figure(3)
    plot(x, -x, 'o', label='x= -y')
    legend(loc='best')

def fig_4():
    figure(4)
    plot(x, ones(len(x)), 'o', label='y=1')
    plot(x, -ones(len(x)), 'o', label='y=-1')
    legend(loc='best')

def fig_5():
    figure(5)
    n, bins, patches = hist(randn(1000), 40, normed=1)
    l, = plot(bins, normpdf(bins, 0.0, 1.0), 'r--', label='fit', linewidth=3)
    legend([l, patches[0]], ['fit', 'hist'], loc='best')

def fig_6():
    figure(6)
    plot(x, 50-x, 'o', label='y=1')
    plot(x, x-50, 'o', label='y=-1')
    legend(loc='best')

def fig_7():
    figure(7)
    xx = x - (N/2.0)
    plot(xx, (xx*xx)-1225, 'bo', label='$y=x^2$')
    plot(xx, 25*xx, 'go', label='$y=25x$')
    plot(xx, -25*xx, 'mo', label='$y=-25x$')
    legend(loc='best')

def fig_8():
    figure(8)
    b1 = bar(x, x, color='m')
    b2 = bar(x, x[::-1], color='g')
    legend([b1[0], b2[0]], ['up', 'down'], loc='best')

def fig_9():
    figure(9)
    b1 = bar(x, -x)
    b2 = bar(x, -x[::-1], color='r')
    legend([b1[0], b2[0]], ['down', 'up'], loc='best')

def fig_10():
    figure(10)
    b1 = bar(x, x, bottom=-100, color='m')
    b2 = bar(x, x[::-1], bottom=-100, color='g')
    b3 = bar(x, -x, bottom=100)
    b4 = bar(x, -x[::-1], bottom=100, color='r')
    legend([b1[0], b2[0], b3[0], b4[0]], ['bottom right', 'bottom left',
                                          'top left', 'top right'],
           loc='best')

if __name__ == '__main__':
    nfigs = 10
    figures = [int(f) for f in sys.argv[1:]]
    if len(figures) == 0:
        figures = range(1, nfigs+1)

    for fig in figures:
        fn_name = "fig_%d" % fig
        fn = globals()[fn_name]
        fn()
        
    show()