python - Matplotlib 在每个条形图上方绘制线条

Question

我想在此图表中的每个条形图上方绘制一条水平线。每个条形的 y 轴位置取决于变量“目标”。我想使用 axhline(如果可能)或 Line2D，因为我需要能够修改线型、颜色、长度和宽度。

import matplotlib.pyplot as plt
plt.rcdefaults()
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline


# Example data
people = ('Tom', 'Dick', 'Harry', 'Slim', 'Jim')

#Here are the targets that I want to use 
#to plot horizontal lines above each bar...
targets = (6,6,8,6,9)

ind = np.arange(len(people))
performance = 3 + 10 * np.random.rand(len(people))
error = np.random.rand(len(people))

plt.bar(ind, performance, align='center')
plt.xticks(ind, people)

plt.show()

提前致谢!

Answer 1

您需要将x_start 和x_end 提供给.hlines()。它们可以是 numpy.array，在这种情况下，每个元素确定每个线段的起点/终点:

import matplotlib.pyplot as plt
plt.rcdefaults()
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline


# Example data
people = ('Tom', 'Dick', 'Harry', 'Slim', 'Jim')

#Here are the targets that I want to use 
#to plot horizontal lines above each bar...
targets = (6,6,8,6,9)

ind = np.arange(len(people))
performance = 3 + 10 * np.random.rand(len(people))
error = np.random.rand(len(people))

Bars = plt.bar(ind, performance, align='center')
_ = plt.xticks(ind, people)

#if you want your hlines to align with the bars.
#i.e. start and end at the same x coordinates:

x_start = np.array([plt.getp(item, 'x') for item in Bars])
x_end   = x_start+[plt.getp(item, 'width') for item in Bars]

plt.hlines(targets, x_start, x_end)