如何在python中从多个dataframe创建单个dataframe？

import pandas as pd

# 创建多个DataFrame示例
df1 = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]})
df2 = pd.DataFrame({'A': [7, 8, 9], 'B': [10, 11, 12]})

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

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

import pandas as pd

# 创建多个DataFrame示例
df1 = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]})
df2 = pd.DataFrame({'A': [7, 8, 9], 'B': [10, 11, 12]})

# 将df2追加到df1的末尾
result = df1.append(df2)

import pandas as pd

# 创建多个DataFrame示例
df1 = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6], 'key': ['K1', 'K2', 'K3']})
df2 = pd.DataFrame({'C': [7, 8, 9], 'D': [10, 11, 12], 'key': ['K1', 'K2', 'K3']})

# 根据key列合并多个DataFrame
result = pd.merge(df1, df2, on='key')

import pandas as pd

# 创建多个DataFrame示例
df1 = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]}, index=['K1', 'K2', 'K3'])
df2 = pd.DataFrame({'C': [7, 8, 9], 'D': [10, 11, 12]}, index=['K1', 'K2', 'K3'])

# 根据索引连接多个DataFrame
result = df1.join(df2)