11. 学习 + 练习
import numpy as np
import pandas as pd
df = pd.DataFrame(np.random.rand(16).reshape(8, 2) * 100, columns=['a', 'b'])
print(df.head(2))
print(df.tail())
print(df.T)
df = pd.DataFrame(np.random.rand(16).reshape(4, 4), columns=['a', 'b', 'c', 'd'])
df['e'] = 10
print(df)
df.loc[4] = 20
print(df)
df[['a', 'c']] = 5
print(df)
df.iloc[::2] = 101
print(df)
del df['e']
print(df)
print(df.drop(0))
print(df.drop([1, 2]))
print(df.drop(['d'], axis=1))
df1 = pd.DataFrame(np.random.rand(16).reshape(4, 4), columns=['a', 'b', 'c', 'd'])
df2 = pd.DataFrame(np.random.rand(16).reshape(8, 2), columns=['a', 'b'])
print(df1 + df2)
df1 = pd.DataFrame(np.random.rand(16).reshape(4, 4)*100, columns=['a', 'b', 'c', 'd'])
print(df1.sort_values(['a'], ascending=True))
print(df1.sort_values(['a'], ascending=False))
print(df1.sort_values(['a', 'c']))
print(df1.sort_index())