如何求曲线下面积

Question

我是 Python 初学者。

曲线（x，y）有两个数据文件：https://drive.google.com/open?id=1ZB39G3SmtamjVjmLzkC2JefloZ9iShpO

如何求曲线下的两个区域，如图：

黑色区域（A）和红色区域（B）

我只知道如何求总面积：

from scipy.integrate import trapz

with open('./x_data.txt', 'rt') as f:
    x_file = f.read()

with open('./y_data.txt', 'rt') as f:
    y_file = f.read()

xlist = []
for line in x_file.split('\n'):
    if line: 
        xlist.append(float(line.strip()))
ylist = []
for line in y_file.split('\n'):
    if line: 
        ylist.append(float(line.strip()))

if len(xlist) != len(ylist):
    print(len(xlist), len(ylist))
    raise Exception('X and Y have different length')

xData = np.array(xlist)
yData = np.array(ylist)

area = trapz(y = yData, x = xData)
print("area =", area)

Answer 1

您可以使用辛普森规则或梯形规则来计算图形下的面积，给定一个定期间隔的 y 值表。

from scipy.integrate import simps
from numpy import trapz

参考：Calculating the area under a curve given a set of coordinates, without knowing the function