matplotlib（矩形）中的填充错误栏

Question

是否可以在matplotlib中制作这样的情节？我只关心红色填充的矩形，用errorbar轻松完成十字架。

Answer 1

不幸的是errorbar无法执行此操作，但您可以根据错误数据创建PatchCollection，这可以轻松添加到轴中。有关如何执行此操作的示例，请参阅此快速脚本。

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import PatchCollection
from matplotlib.patches import Rectangle

# Number of data points
n=5

# Dummy data
x=np.arange(0,n,1)
y=np.random.rand(n)*5.

# Dummy errors (above and below)
xerr=np.random.rand(2,n)
yerr=np.random.rand(2,n)

# Create figure and axes
fig,ax = plt.subplots(1)

# Plot data points
ax.errorbar(x,y,xerr=xerr,yerr=yerr,fmt='None',ecolor='k')

# Function to plot error boxes
def makeErrorBoxes(xdata,ydata,xerror,yerror,fc='r',ec='None',alpha=0.5):

    # Create list for all the error patches
    errorboxes = []

    # Loop over data points; create box from errors at each point
    for xc,yc,xe,ye in zip(xdata,ydata,xerror.T,yerror.T):
        rect = Rectangle((xc-xe[0],yc-ye[0]),xe.sum(),ye.sum())
        errorboxes.append(rect)

    # Create patch collection with specified colour/alpha
    pc = PatchCollection(errorboxes,facecolor=fc,alpha=alpha,edgecolor=ec)

    # Add collection to axes
    ax.add_collection(pc)

# Call function to create error boxes
makeErrorBoxes(x,y,xerr,yerr)

# Add some space around the data points on the axes
ax.margins(0.1)

plt.show()

Answer 2

使用matplotlib.patches绘制正方形非常简单，例如：

import matplotlib.pyplot as pl
import matplotlib.patches

pl.figure()
ax = pl.gca()
ax.add_patch(
   matplotlib.patches.Rectangle(
       (1.0, 1.0), # x, y
       2.0,        # width
       2.0,        # height
       color='r', alpha=0.5
   ) )
ax.set_aspect(1)

pl.xlim(0,4)
pl.ylim(0,4)