I have two datasets

id <- c(1,2,3,4,5)
value1 <- c(20, 10, 15, 20, 30)
month <- c(2, 3, 4, 2, 3)
df1 <- dataframe(id,value1,month)

and the second dataset

id <- c(1,2,3,4,5)
value2 <- c(30, 25, 10, 30, 20)
month <- c(2, 3, 2, 2, 4)
df2 <- dataframe(id,value2,month)

The wanted output is a combined dataset(df3) with (id,value1,value2,month). However, only the id's with matching months should be displayed so id 3 and 5 should not be displayed in df3

CodePudding user response：

simple joins:

base

merge(df1, df2, by = c('id', 'month'))

dplyr

dplyr::inner_join(df1, df2, by = c('id', 'month'))