python画分布图

# -*- coding: cp936 -*-
import numpy as np
import matplotlib.pyplot as plt

step = 0.1
data = [0]*((int)(44/step))

f = open('123.txt','r')
while True:
    line = f.readline()
    if not line:
        break
    d = (float)(line)
    index = (int)((d+22)/step)
    data[index] = data[index] + 1

plt.figure()
x = np.linspace(-22, 22, 440)
plt.xlim(-22,22)
plt.plot(x, data)
plt.show()