如何在Python中使用字符串轴而不是整数来绘制混淆矩阵

问题描述

我正在关注上一个关于如何在Matplotlib中绘制混淆矩阵的主题.脚本如下:

I am following a previous thread on how to plot confusion matrix in Matplotlib. The script is as follows:

from numpy import *
import matplotlib.pyplot as plt
from pylab import *

conf_arr = [[33,2,0,0,0,0,0,0,0,1,3], [3,31,0,0,0,0,0,0,0,0,0], [0,4,41,0,0,0,0,0,0,0,1], [0,1,0,30,0,6,0,0,0,0,1], [0,0,0,0,38,10,0,0,0,0,0], [0,0,0,3,1,39,0,0,0,0,4], [0,2,2,0,4,1,31,0,0,0,2], [0,1,0,0,0,0,0,36,0,2,0], [0,0,0,0,0,0,1,5,37,5,1], [3,0,0,0,0,0,0,0,0,39,0], [0,0,0,0,0,0,0,0,0,0,38] ]

norm_conf = []
for i in conf_arr:
        a = 0
        tmp_arr = []
        a = sum(i,0)
        for j in i:
                tmp_arr.append(float(j)/float(a))
        norm_conf.append(tmp_arr)

plt.clf()
fig = plt.figure()
ax = fig.add_subplot(111)
res = ax.imshow(array(norm_conf), cmap=cm.jet, interpolation='nearest')


for i,j in ((x,y) for x in xrange(len(conf_arr))
            for y in xrange(len(conf_arr[0]))):
    ax.annotate(str(conf_arr[i][j]),xy=(i,j))

cb = fig.colorbar(res)
savefig("confusion_matrix.png", format="png")

我想更改轴以显示字母字符串，例如(A，B，C，...)而不是整数(0,1,2,3，..10).一个人怎么能做到这一点.谢谢.

I would like to change the axis to show string of letters, say (A, B, C,...) rather than integers (0,1,2,3, ..10). How can one do that. Thanks.

musa

推荐答案

以下是我猜测的所需内容:

Here's what I'm guessing you want:

import numpy as np
import matplotlib.pyplot as plt

conf_arr = [[33,2,0,0,0,0,0,0,0,1,3],
            [3,31,0,0,0,0,0,0,0,0,0],
            [0,4,41,0,0,0,0,0,0,0,1],
            [0,1,0,30,0,6,0,0,0,0,1],
            [0,0,0,0,38,10,0,0,0,0,0],
            [0,0,0,3,1,39,0,0,0,0,4],
            [0,2,2,0,4,1,31,0,0,0,2],
            [0,1,0,0,0,0,0,36,0,2,0],
            [0,0,0,0,0,0,1,5,37,5,1],
            [3,0,0,0,0,0,0,0,0,39,0],
            [0,0,0,0,0,0,0,0,0,0,38]]

norm_conf = []
for i in conf_arr:
    a = 0
    tmp_arr = []
    a = sum(i, 0)
    for j in i:
        tmp_arr.append(float(j)/float(a))
    norm_conf.append(tmp_arr)

fig = plt.figure()
plt.clf()
ax = fig.add_subplot(111)
ax.set_aspect(1)
res = ax.imshow(np.array(norm_conf), cmap=plt.cm.jet,
                interpolation='nearest')

width, height = conf_arr.shape

for x in xrange(width):
    for y in xrange(height):
        ax.annotate(str(conf_arr[x][y]), xy=(y, x),
                    horizontalalignment='center',
                    verticalalignment='center')

cb = fig.colorbar(res)
alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
plt.xticks(range(width), alphabet[:width])
plt.yticks(range(height), alphabet[:height])
plt.savefig('confusion_matrix.png', format='png')

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