python - colorbar 查找颜色段的宽度

Question

我有一个颜色条，它有几个颜色块。我怎样才能找到每个颜色段的宽度，然后我可以在其他地方打印出来。我试过 mouseevent.ydata 等，但只输出你点击的地方。有没有办法可以得到色段的宽度？提前致谢

Answer 1

这是 matplotlib 站点中一个演示的修改示例，它还打印出绘制颜色条的路径。

使用iPython其方便的自动完成功能，您可以找出类的成员；

cb.[Press Tab]
cb.add_checker        cb.extend             cb.set_cmap
cb.add_lines          cb.filled             cb.set_colorbar
cb.alpha              cb.formatter          cb.set_label
cb.autoscale          cb.get_array          cb.set_norm
cb.autoscale_None     cb.get_clim           cb.set_ticklabels
cb.ax                 cb.get_cmap           cb.set_ticks
cb.boundaries         cb.lines              cb.solids
cb.callbacksSM        cb.locator            cb.spacing
cb.changed            cb.mappable           cb.to_rgba
cb.check_update       cb.norm               cb.update_bruteforce
cb.cmap               cb.orientation        cb.update_dict
cb.colorbar           cb.outline            cb.update_normal
cb.config_axis        cb.patch              cb.update_ticks
cb.dividers           cb.set_alpha          cb.values
cb.draw_all           cb.set_array          cb.vmax
cb.drawedges          cb.set_clim           cb.vmin

所以我只是尝试了这些。solids似乎最有希望。

In [53]: print cb.solids
<matplotlib.collections.QuadMesh object at 0xb1a620c>

然后我只是查看了Quadmesh 的文档，发现了一些看起来很有希望的东西。

#!/usr/bin/env python
"""
Use a pcolor or imshow with a custom colormap to make a contour plot.

Since this example was initially written, a proper contour routine was
added to matplotlib - see contour_demo.py and
http://matplotlib.sf.net/matplotlib.pylab.html#-contour.
"""

from pylab import *


delta = 0.01
x = arange(-3.0, 3.0, delta)
y = arange(-3.0, 3.0, delta)
X,Y = meshgrid(x, y)
Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = Z2 - Z1 # difference of Gaussians

cmap = cm.get_cmap('PiYG', 11)    # 11 discrete colors

im = imshow(Z, cmap=cmap, interpolation='bilinear',
            vmax=abs(Z).max(), vmin=-abs(Z).max())
#axis('off')
cb = colorbar()

for path in cb.solids.get_paths():
    print path

show()

然后是终端输出：

Path([[ 0.          0.        ]
 [ 1.          0.        ]
 [ 1.          0.09090909]
 [ 0.          0.09090909]
 [ 0.          0.        ]], None)
Path([[ 0.          0.09090909]
 [ 1.          0.09090909]
 [ 1.          0.18181818]
 [ 0.          0.18181818]
 [ 0.          0.09090909]], None)
Path([[ 0.          0.18181818]
 [ 1.          0.18181818]
 [ 1.          0.27272727]
 [ 0.          0.27272727]
 [ 0.          0.18181818]], None)
Path([[ 0.          0.27272727]
 [ 1.          0.27272727]
 [ 1.          0.36363636]
 [ 0.          0.36363636]
 [ 0.          0.27272727]], None)
Path([[ 0.          0.36363636]
 [ 1.          0.36363636]
 [ 1.          0.45454545]
 [ 0.          0.45454545]
 [ 0.          0.36363636]], None)
Path([[ 0.          0.45454545]
 [ 1.          0.45454545]
 [ 1.          0.54545455]
 [ 0.          0.54545455]
 [ 0.          0.45454545]], None)
Path([[ 0.          0.54545455]
 [ 1.          0.54545455]
 [ 1.          0.63636364]
 [ 0.          0.63636364]
 [ 0.          0.54545455]], None)
Path([[ 0.          0.63636364]
 [ 1.          0.63636364]
 [ 1.          0.72727273]
 [ 0.          0.72727273]
 [ 0.          0.63636364]], None)
Path([[ 0.          0.72727273]
 [ 1.          0.72727273]
 [ 1.          0.81818182]
 [ 0.          0.81818182]
 [ 0.          0.72727273]], None)
Path([[ 0.          0.81818182]
 [ 1.          0.81818182]
 [ 1.          0.90909091]
 [ 0.          0.90909091]
 [ 0.          0.81818182]], None)
Path([[ 0.          0.90909091]
 [ 1.          0.90909091]
 [ 1.          1.        ]
 [ 0.          1.        ]
 [ 0.          0.90909091]], None)

我不知道这些数字在什么坐标空间上。对不起。