如何通过键将多个数据框行合并为一个行？

import pandas as pd

# 创建示例数据框
df1 = pd.DataFrame({'key': ['A', 'B', 'C'], 'value1': [1, 2, 3]})
df2 = pd.DataFrame({'key': ['A', 'B', 'D'], 'value2': [4, 5, 6]})
df3 = pd.DataFrame({'key': ['A', 'C', 'E'], 'value3': [7, 8, 9]})

# 合并数据框
merged_df = pd.merge(df1, df2, on='key', how='inner')
merged_df = pd.merge(merged_df, df3, on='key', how='inner')

# 输出合并后的结果
print(merged_df)

  key  value1  value2  value3
0   A       1       4       7