python

python示例1# -*- coding:utf-8 -*-  import mathimport matplotlib.pyplot as pltif __name__ == '__main__':    x = [float(i) / 100.0 for i in range(1, 300)]    y = [math.log(i) for i in x]    plt.plot(x, y, 'r-', linewidth=3, label='log Curve')    a = [x[20], x[175]]    b = [y[20], y[175]]    plt.plot(a, b, 'g-', linewidth=2)    plt.plot(a, b, 'b*', markersize=15, alpha=0.75)    plt.legend(loc='upper left')    plt.grid(True)  # 显示网格      plt.xlabel('x')    plt.ylabel('log(x)')    plt.show()python示例2import numpy as npimport matplotlib.pyplot as pltif __name__ == '__main__':    u = np.random.uniform(0.0, 1.0, 10000)  # 产生10000个[0,1)的数      plt.hist(u, 80, facecolor='g', alpha=0.2)  # 对应x轴,指定bin(箱子)的个数,80条状图,颜色      plt.grid(True)    plt.show()    times = 10000    for time in range(times):        u += np.random.uniform(0.0, 1.0, 10000)    print(len(u))    u /= times    print(len(u))    plt.hist(u, 80, facecolor='g', alpha=0.75)    plt.grid(True)    plt.show()# 对数函数的速度  import mathimport matplotlib.pyplot as pltimport numpy as npif __name__ == '__main__':    x = np.arange(0.05, 3, 0.05)    y1 = [math.log(a, 1.5) for a in x]    plt.plot(x, y1, linewidth=2, color='r', label='log1.5(x)')    plt.plot([1, 1], [y1[0], y1[-1]], 'r--', linewidth=2)    y2 = [math.log(a, 2) for a in x]    plt.plot(x, y2, linewidth=2, color='g', label='log2(x)')    y3 = [math.log(a, 3) for a in x]    plt.plot(x, y3, linewidth=2, color='b', label='log3(x)')    plt.legend(loc='lower right')    plt.grid(True)    plt.show()import matplotlib.pyplot as pltdef first_digital(x):    while x >= 10:        x /= 10    return xif __name__ == '__main__':    n = 1    frequency = [0] * 9    for i in range(1,100):        n *= i        m = int(first_digital(n) - 1)        frequency[m] += 1    print(frequency)    plt.plot(frequency,'r-',linewidth=2)    plt.plot(frequency,'go',markersize=8)    plt.grid(True)    plt.show()