python - Matplotlib - 想要绘制以 x 轴中间为中心的函数

Question

import numpy as np
import math
import matplotlib.pyplot as plt
import csv

def sig(a, x):
    return 1 / (1 + math.exp(-a*x))
def cos(x):
    return (math.cos(x)+1)/2

a = []
b = []
c = []
j = np.arange(-math.pi,0, 0.0001)
g = np.arange(-math.pi,0, 0.0002)
k = np.arange(-math.pi,0, 0.0010)



csvfile = "data.csv"
idx, value =  "Index","Value"
csvRow = [idx, value]
with open(csvfile, "w", newline='') as fp:
    wr = csv.writer(fp, dialect = "excel")
    wr.writerow(csvRow)


    for i in range(0, len(j), 1):
        a.append(cos(j[i]))
        ##wr.writerow([i,sig(g, j[i])])

    for i in range(0, len(g), 1):
        b.append(cos(g[i]))

    for i in range(0, len(k), 1):
        c.append(cos(k[i]))

    fp.close()

plt.plot(a)
plt.plot(b)
plt.plot(c) 

plt.show()

我想绘制这三个 cos 函数来比较陡度。为了实现这一点，我想让所有功能都以 x 轴的中间为中心，我该如何实现呢？ 目前情节看起来像这样

标签： pythonmatplotlibvisualization