我正在尝试绘制一个值矩阵,并希望添加网格线以使值之间的边界更清晰。不幸的是,imshow决定在每个体素的中间找到刻度线。是否有可能
a)删除刻度线,但将标签留在同一位置并且 b)在像素边界之间添加网格线?
import matplotlib.pyplot as plt
import numpy as np
im = plt.imshow(np.reshape(np.random.rand(100), newshape=(10,10)),
interpolation='none', vmin=0, vmax=1, aspect='equal');
ax = plt.gca();
ax.set_xticks(np.arange(0, 10, 1));
ax.set_yticks(np.arange(0, 10, 1));
ax.set_xticklabels(np.arange(1, 11, 1));
ax.set_yticklabels(np.arange(1, 11, 1));
ax.grid(color='w', linestyle='-', linewidth=2)
网格线位于错误位置的图像:
Serenity建议的解决方案代码:
plt.figure()
im = plt.imshow(np.reshape(np.random.rand(100), newshape=(10,10)),
interpolation='none', vmin=0, vmax=1, aspect='equal');
ax = plt.gca();
# Major ticks
ax.set_xticks(np.arange(0, 10, 1));
ax.set_yticks(np.arange(0, 10, 1));
# Labels for major ticks
ax.set_xticklabels(np.arange(1, 11, 1));
ax.set_yticklabels(np.arange(1, 11, 1));
# Minor ticks
ax.set_xticks(np.arange(-.5, 10, 1), minor=True);
ax.set_yticks(np.arange(-.5, 10, 1), minor=True);
# Gridlines based on minor ticks
ax.grid(which='minor', color='w', linestyle='-', linewidth=2)
您可以通过将extent
参数传递给imshow
来移动像素。 extent
是一个4元素的标量列表(左,右,下,上):
foo = np.random.rand(35).reshape(5, 7)
# This keeps the default orientation (origin at top left):
extent = (0, foo.shape[1], foo.shape[0], 0)
_, ax = plt.subplots()
ax.imshow(foo, extent=extent)
ax.grid(color='w', linewidth=2)
ax.set_frame_on(False)
人们可以发现使用plt.pcolor
或plt.pcolormesh
更容易:
data = np.random.rand(10, 10)
plt.pcolormesh(data, edgecolors='k', linewidth=2)
ax = plt.gca()
ax.set_aspect('equal')
虽然,他们和plt.imshow
之间存在一些差异,但最明显的是图像被Y轴交换(你可以通过添加ax.invert_yaxis()
来轻松地将其反转回来)。有关进一步讨论,请参见:When to use imshow over pcolormesh?