没用，随便写的（Dec_8_2022）

import numpy as np
from PIL import Image
import pandas as pd
import matplotlib.pyplot as plt

# 第一个
# data = 2*np.random.rand(10000, 2) - 1
# # 原本data∈[0,1]想办法改变值域
# # 现在data∈[-1，1]
# x = data[:, 0]
# y = data[:, 1]
# idx = x**2 + y**2 < 1
# hole = x**2 + y**2 < 0.25
# idx = np.logical_and(idx, ~hole)
# plt.plot(x[idx], y[idx], 'go', markersize=1)
# plt.show()

# 第二个
# p = np.random.rand(10000)
# np.set_printoptions(edgeitems=5000, suppress=True)
# plt.hist(p, bins=20, color='g', edgecolor='k')
# plt.show()

# 第三个
# N = 10000
# times = 100
# z = np.zeros(N)
# for i in range(times):
#     z += np.random.rand(N)
# z /= times
# plt.hist(z, bins=20, color='m', edgecolor='k')
# plt.show()

# 第四个
# d = np.random.rand(30, 4)
# print(d)
# print(type(d))
# data = pd.DataFrame(data=d, columns=list('abcd'))
# print('='*50)
# print(data)
# print(type(data))
# print(data[list('ab')])
# data.to_csv('data.csv', index=False, header=True)
# print('文件保存成功.')

# 第五个
# [-4, 2]=[0,1]*6-4
# d = 6*np.random.rand(10000) - 4
# plt.plot(d, 'r.')
# plt.show()

# 第六个
# x = np.linspace(0, 1, 100)
# print(x)
# y = x**x
# plt.plot(x, y, 'r-', linewidth=3)
# plt.show()

# 第七个
# a = np.arange(1, 10000)
# print(np.sqrt(6*np.sum(1 / (a**2))))

# 第八个
# image_file = 'lena.png'
# height = 100
# img = Image.open(image_file)
# img_width, img_height = img.size
# width = int(1.8 * height * img_width // img_height)
# img = img.resize((width, height), Image.ANTIALIAS)
# pixels = np.array(img.convert('L'))
# print('type(pixels) = ', type(pixels))
# print(pixels.shape)
# print(pixels)
# chars = "MNHQ$OC?7>!:-;."
# N = len(chars)
# step = 256 // N
# print(N)
# result = ''
# for i in range(height):
#     for j in range(width):
#         result += chars[pixels[i][j] // step]
#     result += '\n'
# with open('text.txt', mode='w') as f:
#     f.write(result)