python – matplotlib colormap：不要调整大小

2019年8月4日 302次阅读

我正在使用matplotlib绘制一个混淆矩阵：

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

conf_arr_hs = [[90, 74],
                [33, 131]]
norm_conf_hs = []
for i in conf_arr_hs:
    a = 0
    tmp_arr = []
    a = sum(i, 0)
    for j in i:
        tmp_arr.append(float(j)/float(a))
    norm_conf_hs.append(tmp_arr)


confmatmap=cm.binary    
fig = plt.figure()


plt.clf()
ax = fig.add_subplot(111)
res = ax.imshow(np.array(norm_conf_hs), cmap=confmatmap, interpolation='nearest')
for x in xrange(2):
    for y in xrange(2):
        textcolor = 'black'
        if norm_conf_hs[x][y] > 0.5:
            textcolor = 'white'
        ax.annotate("%0.2f"%norm_conf_hs[x][y], xy=(y, x),  horizontalalignment='center', verticalalignment='center', color=textcolor)]

但matplotlib似乎会自动调整颜色变化范围：左下方网格应为浅灰色,因为其对应值为0.2而不是0.0.同样,右下方网格应为深灰色,因为它是0.8而不是1.

我想我错过了任命颜色映射动态范围的步骤.我对matplotlib的文档进行了一些研究,但没有找到我想要的东西.

最佳答案 要显式设置颜色映射范围,您需要使用set_clim命令：

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

plt.ion()

conf_arr_hs = [[90, 74],
                [33, 131]]
norm_conf_hs = []
for i in conf_arr_hs:
    a = 0
    tmp_arr = []
    a = sum(i, 0)
    for j in i:
        tmp_arr.append(float(j)/float(a))
    norm_conf_hs.append(tmp_arr)

confmatmap=plt.cm.binary    
fig = plt.figure()

plt.clf()
ax = fig.add_subplot(111)
res = ax.imshow(np.array(norm_conf_hs), cmap=confmatmap, interpolation='nearest')
res.set_clim(0,1) # set the limits for your color map

for x in xrange(2):
    for y in xrange(2):
        textcolor = 'black'
        if norm_conf_hs[x][y] > 0.5:
            textcolor = 'white'
        ax.annotate("%0.2f"%norm_conf_hs[x][y], xy=(y, x),  horizontalalignment='center', verticalalignment='center', color=textcolor)

点击这里查看更多信息：http://matplotlib.org/api/cm_api.html

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