通过不同的列名合并data.frames，并返回用于匹配的两个列

# 创建两个示例data.frame
df1 <- data.frame(ID = c(1, 2, 3),
                  Name = c("Alice", "Bob", "Charlie"),
                  Age = c(25, 30, 35))

df2 <- data.frame(ID = c(2, 3, 4),
                  City = c("New York", "London", "Tokyo"),
                  Salary = c(5000, 6000, 7000))

# 使用merge()函数按照ID列合并两个data.frame
merged_df <- merge(df1, df2, by = "ID")

# 输出合并后的data.frame
print(merged_df)

  ID    Name Age     City Salary
1  2     Bob  30 New York   5000
2  3 Charlie  35   London   6000