如何在 R 中基于多列合并 DataFrame？

在本文中，我们将讨论如何在 R 编程语言中基于多列合并数据帧。

我们可以使用 merge()函数合并基于多列的两个数据框

语法：

merge(dataframe1, dataframe2, by.x=c(‘column1’, ‘column2’………..,’column n’), by.y=c(‘column1’, ‘column2’………..,’column n’))

where

• dataframe1 is the first dataframe
• dataframe2 is the second dataframe
• by.x represents first dataframe columns
• by.y represents second dataframe columns

让我们创建两个数据框并显示

示例：R 程序创建两个具有 4 列学生数据的数据框

R

# create dataframe1
data1 = data.frame(name=c("manoj", "manoja", "saroja", "ramya"),
                   subjects=c("java", "c/cpp", "python", "R"),
                   city=c("ponnur", "tenali", "hyd", "guntur"),
                   marks=c(89, 90, 78, 89))
  
# create dataframe2
data2 = data.frame(name=c("manoj", "sravya", "saroja", "pavani"),
                   subjects=c("java", "c/html", "python", "php/css"),
                   city=c("ponnur", "hyd", "hyd", "guntur"),
                   marks=c(89, 78, 78, 81))
  
# display
print(data1)
print(data2)

输出：

示例 1：合并 2 列上的数据框

R

# create dataframe1
data1 = data.frame(name=c("manoj", "manoja", "saroja", "ramya"),
                   subjects=c("java", "c/cpp", "python", "R"),
                   city=c("ponnur", "tenali", "hyd", "guntur"),
                   marks=c(89, 90, 78, 89))
  
# create dataframe2
data2 = data.frame(student=c("manoj", "sravya", "saroja", "pavani"),
                   subjects=c("java", "c/html", "python", "php/css"),
                   city=c("ponnur", "hyd", "hyd", "guntur"),
                   exams=c(89, 78, 78, 81))
  
# merge dataframes based on name and subjects from data1
# with student and subjects from data2
merge(data1, data2, by.x=c('name', 'subjects'),
      by.y=c('student', 'subjects'))

输出：

示例 2：基于三列合并数据框。

R

# create dataframe1
data1 = data.frame(name=c("manoj", "manoja", "saroja", "ramya"),
                   subjects=c("java", "c/cpp", "python", "R"),
                   city=c("ponnur", "tenali", "hyd", "guntur"),
                   marks=c(89, 90, 78, 89))
  
# create dataframe2
data2 = data.frame(student=c("manoj", "sravya", "saroja", "pavani"),
                   subjects=c("java", "c/html", "python", "php/css"),
                   city=c("ponnur", "hyd", "hyd", "guntur"),
                   exams=c(89, 78, 78, 81))
  
# merge dataframes based on name,city and subjects from data1
# with student,city and subjects from data2
merge(data1, data2, by.x=c('name', 'subjects', 'city'),
      by.y=c('student', 'subjects', 'city'))

输出：