Pandas将多个数据帧合并为一个

import pandas as pd

# 创建示例数据帧
df1 = pd.DataFrame({'A': [1, 2], 'B': [3, 4]})
df2 = pd.DataFrame({'A': [5, 6], 'B': [7, 8]})

# 按行连接
result = pd.concat([df1, df2], axis=0)
print(result)

# 按列连接
result = pd.concat([df1, df2], axis=1)
print(result)

import pandas as pd

# 创建示例数据帧
df1 = pd.DataFrame({'A': [1, 2], 'B': [3, 4], 'key': ['K1', 'K2']})
df2 = pd.DataFrame({'C': [5, 6], 'D': [7, 8], 'key': ['K1', 'K2']})

# 根据列合并
result = pd.merge(df1, df2, on='key')
print(result)

# 根据索引合并
result = pd.merge(df1, df2, left_index=True, right_index=True)
print(result)

import pandas as pd

# 创建示例数据帧
df1 = pd.DataFrame({'A': [1, 2], 'B': [3, 4]}, index=['K1', 'K2'])
df2 = pd.DataFrame({'C': [5, 6], 'D': [7, 8]}, index=['K1', 'K2'])

# 索引连接
result = df1.join(df2, lsuffix='_left', rsuffix='_right')
print(result)