色条设置刻度格式化器/定位器更改刻度标签

7 投票
1 回答
14500 浏览
提问于 2025-04-16 20:19

大家好,

我想自定义颜色条上的刻度。但是,我发现了一些奇怪的情况。我尝试把刻度格式改回默认的格式(我以为这样应该不会有任何变化),结果却得到了不同的标签。有没有人知道我哪里出错了?还是说这是个bug?

我使用的是从git上获取的matplotlib(版本v1.0.1-961-gb516ae0,git描述)。以下代码生成了两个图:

#http://matplotlib.sourceforge.net/examples/pylab_examples/griddata_demo.html
from numpy.random import uniform, seed
from matplotlib.mlab import griddata
import matplotlib.pyplot as plt
import matplotlib.ticker
import numpy as np
# make up data.
seed(0)
npts = 200
x = uniform(-2,2,npts)
y = uniform(-2,2,npts)
z = x*np.exp(-x**2-y**2)
# define grid
xi = np.linspace(-2.1,2.1,100)
yi = np.linspace(-2.1,2.1,200)
# grid the data.
zi = griddata(x,y,z,xi,yi,interp='linear')

##### FIRST PLOT
plt.figure()
CS  = plt.contour(xi,yi,zi,25,cmap=plt.cm.jet)
bar = plt.colorbar() # draw colorbar
# plot data points.
#plt.scatter(x,y,marker='o',c='b',s=5,zorder=10)
plt.xlim(-2,2)
plt.ylim(-2,2)
plt.title('griddata test (%d points)' % npts)
plt.show()

##### SECOND PLOT
plt.figure()
CS  = plt.contour(xi,yi,zi,25,cmap=plt.cm.jet)
bar = plt.colorbar() # draw colorbar
bar.ax.yaxis.set_minor_locator(matplotlib.ticker.AutoLocator())
bar.ax.yaxis.set_major_locator(matplotlib.ticker.AutoLocator())
# plot data points.
#plt.scatter(x,y,marker='o',c='b',s=5,zorder=10)
plt.xlim(-2,2)
plt.ylim(-2,2)
plt.title('griddata test (%d points)' % npts)
plt.show()

1 个回答

17

我刚找到了解决办法。需要在更改格式器/定位器之后调用

bar.update_ticks()

具体可以参考这个链接:

http://matplotlib.sourceforge.net/api/colorbar_api.html

这样一来,一切就能正常工作了。

更新:

这里还有一段代码,用于更改格式器/定位器。它是基于colorbar代码的内部结构,所以可能还有其他人有更好的解决方案:

#http://matplotlib.sourceforge.net/examples/pylab_examples/griddata_demo.html
from numpy.random import uniform, seed
from matplotlib.mlab import griddata
import matplotlib.pyplot as plt
import matplotlib.ticker
import numpy as np
# make up data.
seed(0)
npts = 200
x = uniform(-2,2,npts)
y = uniform(-2,2,npts)
z = x*np.exp(-x**2-y**2)
# define grid
xi = np.linspace(-2.1,2.1,100)
yi = np.linspace(-2.1,2.1,200)
# grid the data.
zi = griddata(x,y,z,xi,yi,interp='linear')

##### PLOT
plt.figure()
CS  = plt.contour(xi,yi,zi,25,cmap=plt.cm.jet)
bar = plt.colorbar(orientation='horizontal') # draw colorbar


tick_locs   = [-3.9e-1,-2.6e-1,-1.3e-1,0e-1,1.3e-1,2.6e-1,3.9e-1]
tick_labels = ['-0.390','-0.260','-0.130','0','0.13','0.26','0.390']


bar.locator     = matplotlib.ticker.FixedLocator(tick_locs)
bar.formatter   = matplotlib.ticker.FixedFormatter(tick_labels)
bar.update_ticks()

# plot data points.
#plt.scatter(x,y,marker='o',c='b',s=5,zorder=10)
plt.xlim(-2,2)
plt.ylim(-2,2)
plt.title('griddata test (%d points)' % npts)
plt.show()

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