Mastering Data Frame Joins in R: Inner, Outer, Left, and Right Joins Explained

 In R language, you can join data frames using various types of joins, including inner join, outer join, left join, and right join. Here's how you can perform these joins using the merge() function or the dplyr package.

1. Inner Join: An inner join returns only the matching records between two data frames.

Using merge() function:

merged_df <- merge(df1, df2, by = "common_column")

Using dplyr package:

library(dplyr)
merged_df <- inner_join(df1, df2, by = "common_column")

2. Outer Join: An outer join returns all records from both data frames, matching records as well as non-matching records.

Using merge() function:

merged_df <- merge(df1, df2, by = "common_column", all = TRUE)

Using dplyr package:

library(dplyr)
merged_df <- full_join(df1, df2, by = "common_column")

3. Left Join: A left join returns all records from the left data frame and the matching records from the right data frame.

Using merge() function:

merged_df <- merge(df1, df2, by = "common_column", all.x = TRUE)

Using dplyr package:

library(dplyr)
merged_df <- left_join(df1, df2, by = "common_column")

4. Right Join: A right join returns all records from the right data frame and the matching records from the left data frame.

Using merge() function:

merged_df <- merge(df1, df2, by = "common_column", all.y = TRUE)

Using dplyr package:

library(dplyr)
merged_df <- right_join(df1, df2, by = "common_column")

Note: Replace df1 and df2 with the names of your actual data frames, and "common_column" with the column name that both data frames share.