How To Merge Data Frames In R

Hi guys! Today we will share with you a guide on how to merge data frames in R. This is the most basic skill when you work with data in R, so please take a look at the below examples and explanations of two approaches: using full_join() and using merge().

Merge data frames in R

There are different ways to merge data frames in R. Mostly, programmers usually choose two methods: using join() and using merge().

Using full_join()

To merge two dataframes in R, you can use the full_join() function. However, this is not a built-in function, so you have to install a package named dplyr and import it to use first.

Syntax:

full_join(x, y)

Parameters:

• x: This is the first data frame or objects to be merged.
• y: This is the second data frame or objects to be merged.

Suppose you have two tables stored in two csv files. 

Full Name, Address
Ole Grant, 2555 Hammes Ways
Jayme Rippin, 754 Jerrod
Jeffery Bashirian, 4253 Paucek
Carolyne Krajcik, 8927 Predovic
Blankman, 730 Mekhi
Dr. Lydia Konopelski MD, 30005 Skiles

Full Name, Age
Ole Grant, 22
Jayme Rippin, 32
Jeffery Bashirian, 27
Carolyne Krajcik, 31
Blankman, 55
Dr. Lydia Konopelski MD, 87

Now you have to merge them to get the full information:

library(dplyr)
 
# Read file addresses.csv and assign to data frame 'addresses'
addresses <- read.csv(file = 'addresses.csv', sep = ',', header = T)
addresses 
 
# Read file ages.csv and assign to data frame 'ages'
ages <- read.csv(file = 'ages.csv', sep = ',', header = T)
ages
 
# Merge two data frames
full_join(addresses, ages)

Output:

               Full Name            Address  Age
1               Ole Grant  2555 Hammes Ways  22
2            Jayme Rippin        754 Jerrod  32
3       Jeffery Bashirian       4253 Paucek  27
4        Carolyne Krajcik     8927 Predovic  31
5                Blankman         730 Mekhi  55
6 Dr. Lydia Konopelski MD      30005 Skiles  87

In lines 3: We have defined a table named addresses which contains the full name and their addresses of them.

In Lines 7: We also define a data frame named ages containing the information of their age.

Line 12: We use the full_join function to perform merging data frames in R.

As you can see, after merging, we receive a table with three columns; the first column is the full name and the second is the corresponding address of them, and the third one is the corresponding age of them.

Using merge()

There is another way to merge two data frames in R, which is using the R merge function. Its syntax and usage can be found here. We can reuse the data frames in the above solution to make an example for this one:

# Read file addresses.csv and assign to data frame 'addresses'
addresses <- read.csv(file = 'addresses.csv', sep = ',', header = T)
addresses 
 
# Read file ages.csv and assign to data frame 'ages'
ages <- read.csv(file = 'ages.csv', sep = ',', header = T)
ages
 
# Merge two data frames
merge(addresses, ages)

Output:

               Full Name           Address Age
1                Blankman         730 Mekhi  55
2        Carolyne Krajcik     8927 Predovic  31
3 Dr. Lydia Konopelski MD      30005 Skiles  87
4            Jayme Rippin        754 Jerrod  32
5       Jeffery Bashirian       4253 Paucek  27
6               Ole Grant  2555 Hammes Ways  22

Do you see any difference between the two outputs in each solution? They are different in the order of the rows, which is a result of the different algorithm when implementing the function. However, the corresponding information after merging for each full name doesn’t change and hence this solution also works correctly.

Actually you can consider using any function that you want. But this solution doesn’t require you to import any package and therefore you just need to call the R merge() function to use it because it is built-in.

Summary

We have learned how to merge data frames in R by using two different methods. It would help if you considered that the second approach has more advantages than others. You can learn more about R with us here.

Maybe you are interested:

• For Loops In R: The Syntax And Code Example
• Merge In R: What is merge() in R and Example
• Merge multiple data frames in r

Edward Anderson

I’m Edward Anderson. My current job is as a programmer. I’m majoring in information technology and 5 years of programming expertise. Python, C, C++, Javascript, Java, HTML, CSS, and R are my strong suits. Let me know if you have any questions about these programming languages.

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Name of the university: HCMUT
Major: CS
Programming Languages: Python, C, C++, Javascript, Java, HTML, CSS, R