python中的Matplotlib非对称错误栏打印

尝试绘制从负值到正值的非对称条时出错。我修改了文档中的示例：

import numpy as np
import matplotlib.pyplot as plt

# example data
x = np.arange(0, 4, 1)
y = -0.2* x


# example error bar values that vary with x-position
error = 0.1 + 0.2 * x

# error bar values w/ different -/+ errors that
# also vary with the x-position
lower_error = -1 * error
upper_error = 4* error
asymmetric_error = [lower_error, upper_error]

plt.errorbar(x, y, yerr=asymmetric_error, fmt='.', ecolor = 'red')
plt.show()

它给出了以下曲线图：

但不对称误差的值如下：

数组（[-0.1，-0.3，-0.5，-0.7]），数组（[0.4,1.2,2,2.8]）]

---

这似乎符合文档的要求，因此我不确定是什么原因导致了这一点。

在较低的错误前面不需要负片

import numpy as np
import matplotlib.pyplot as plt

# example data
x = np.arange(0, 4, 1)
y = -0.2* x


# example error bar values that vary with x-position
error = 0.1 + 0.2 * x

# error bar values w/ different -/+ errors that
# also vary with the x-position
lower_error =  error
upper_error =  4*error
asymmetric_error = np.array(list(zip(lower_error, upper_error))).T

plt.errorbar(x, y, yerr=asymmetric_error, fmt='.', ecolor = 'red')
plt.show()

输出：