使用matplotlib在网格中显示值

Question

我正在尝试为一些数据生成热图，我的代码如下所示：

data = [['basis', 2007, 2008],
        [1, 2.2, 3.4],
        [2, 0, -2.2],
        [3, -4.1, -2.5],
        [4, -5.8, 1.2],
        [5, -5.4, -3.6],
        [6, 1.4, -5.9]]

x_header = data[0][1:]
y_header = [i for i in range(1, 13)]
data=data[1:]
for i in range(len(data)):
    data[i] = data[i][1:]
arr = np.array(data)
fig, ax = plt.subplots()
#heatmap = plt.pcolor(arr, cmap = 'RdBu')
norm = MidpointNormalize(midpoint=0)
im = ax.imshow(data, norm=norm, cmap=plt.cm.seismic, interpolation='none')

ax.set_xticks(np.arange(arr.shape[1]), minor=False)
ax.set_yticks(np.arange(arr.shape[0]), minor=False)
ax.xaxis.tick_top()
ax.set_xticklabels(x_header, rotation=90)
ax.set_yticklabels(y_header)

fig.colorbar(im)
plt.show()

它生成图像

我也想在网格内显示值。有什么办法吗？

Answer 1

当然，只需执行以下操作：

import matplotlib.pyplot as plt
import numpy as np

data = np.random.random((4, 4))

fig, ax = plt.subplots()
# Using matshow here just because it sets the ticks up nicely. imshow is faster.
ax.matshow(data, cmap='seismic')

for (i, j), z in np.ndenumerate(data):
    ax.text(j, i, '{:0.1f}'.format(z), ha='center', va='center')

plt.show()

但是，标签很难看到，因此您可能需要在它们周围放置一个框：

import matplotlib.pyplot as plt
import numpy as np

data = np.random.random((4, 4))

fig, ax = plt.subplots()
# Using matshow here just because it sets the ticks up nicely. imshow is faster.
ax.matshow(data, cmap='seismic')

for (i, j), z in np.ndenumerate(data):
    ax.text(j, i, '{:0.1f}'.format(z), ha='center', va='center',
            bbox=dict(boxstyle='round', facecolor='white', edgecolor='0.3'))

plt.show()

另外，在许多情况下，这样ax.annotate做更为有用ax.text。它在放置文本方面更加灵活，但也更加复杂。在这里看看示例：http
:
//matplotlib.org/users/annotations_guide.html