Often you may want to combine two columns into one in R. For example, suppose you have a data frame with three columns:
month year value 10 2019 15 10 2020 13 11 2020 13 11 2021 19 12 2021 22
You may wish to combine the month and year column into a single column called date:
date value 2019_10 15 2020_10 13 2020_11 13 2021_11 19 2021_12 22
This tutorial explains two ways to quickly do this in R.
Method 1: Use the Paste Function from Base R
The following code shows how to use the paste function from base R to combine the columns month and year into a single column called date:
#create data frame data <- data.frame(month=c(10, 10, 11, 11, 12), year=c(2019, 2020, 2020, 2021, 2021), value=c(15, 13, 13, 19, 22)) #view data frame data #combine year and month into one column data$date <- paste(data$year, data$month, sep="_") #view new data frame data month year value date 1 10 2019 15 2019_10 2 10 2020 13 2020_10 3 11 2020 13 2020_11 4 11 2021 19 2021_11 5 12 2021 22 2021_12
Once we’ve combined the two columns, we can remove the old ones if we’d like:
data_new <- data[c("date", "value")]
data_new
date value
1 2019_10 15
2 2020_10 13
3 2020_11 13
4 2021_11 19
5 2021_12 22
Method 2: Use the Unite Function from Tidyr
The following code shows how to use the unite function from the tiydr package to combine the columns month and year into a single column called date:
#load tidyr package library(tidyr) #create data frame data <- data.frame(month=c(10, 10, 11, 11, 12), year=c(2019, 2020, 2020, 2021, 2021), value=c(15, 13, 13, 19, 22)) #combine year and month into one column unite(data, date, c(year, month)) date value 1 2019_10 15 2 2020_10 13 3 2020_11 13 4 2021_11 19 5 2021_12 22
Notice that both methods produce identical results.
You can find the complete documentation for the unite function here.
