How to Merge DataFrames Based on Multiple Columns in R?

In this article, we will discuss how to merge dataframes based on multiple columns in R Programming Language.

We can merge two  dataframes based on multiple columns  by using merge() function

Syntax:

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

Let create two dataframes and display

Example: R program to create two dataframes with 4 columns of student data

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)

Output:

Example 1 : Merge dataframes on 2 columns

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'))

Output:

Example 2: Merge the dataframes based on three columns.

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'))

Output: