In this short R tutorial, you will learn how to add an empty column to a dataframe in R. Specifically, you will learn 1) to add an empty column using base R, 2) add an empty column using the add_column function from the package tibble and we are going to use a pipe (from dplyr). Now, dplyr comes with a lot of handy functions that, apart from adding columns, makes it easy to remove a column from the R dataframe (e.g., using the select() function). Both tibble and dplyr are part of the tidyverse package. 

The outline of this post is as follows:

  1. Reading Data from an Excel File
  2. How to Add an Empty Column to the Dataframe with:
    • Base R
    • add_column()
  3. How to Add Multiple Empty Columns with:
    • Base R
    • add_column()

First, before reading the .xlsx file I will go through what you need to follow this post. After that, you’ll find a syntax answering the question “How do I add an empty column to a DataFrame in R?”. in the next section, we will get into more details about adding columns. Now, in all the examples we will cover how to insert empty strings or missing values as both could be considered being empty. 

Prerequisites

Obviously, you need to have R installed to follow this tutorial. Furthermore, if you want to add a column using tibble (and dplyr) you need to install these packages. Finally, if you are going to read the example .xlsx file you will also need to install the readr package. Note, however, that if you install the tidyverse package you will get tibble, dplyr and readr.

I would highly recommend installing tidyverse as you can also easily calculate descriptive statistics, visualize data (e.g., scatter plots with ggplot2), among other things. Installing the r packages can be done using the install.packages() function:

install.packages(c('tibble', 'dplyr', 'readr'))

If you want to install tidyverse just type install.packages('tidyverse') instead. Another great package, part of the tidyverse package, is lubridate. If you are working with time series data this package can be used to use R to extract year from date but also to extract day and to extract time. Now that you should be set with these useful packages we can start reading an Excel file and, after that, go on by adding columns. But first, let’s give a short answer to the question that may have brought you here:

How do I add an empty column to a DataFrame in R?

How to add an empty column to dataframe in R
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The easiest way to add an empty column to a dataframe in R is to use the add_column() method: dataf %>% add_column(new_col = NA). Note, that this includes installing dplyr or tidyverse. In the next section, you will get more descriptive examples on how to insert columns to the dataframe.

Finally, before we read the example date, it may be worth mentioning that we can also use R to add a column to a dataframe based on conditions of other columns.

Reading Data from an Excel (.xlsx) File

Now, before getting into more detail on how to append a column we will read some example data using readxl:

library(readxl)
dataf <-  read_xlsx('example_sheets.xlsx',
                    skip = 2)

Briefly explained, in the code chunk above example_sheets.xlsx (click to download) is stored in the same directory as the R script. The second argument is used to skip the first 2 rows containing some information (i.e., the column names are on the 3rd row). Here are the first 5 rows of the imported data:

R Dataframe we are going to add an empty column
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First five rows of dataframe to which we will add columns

As a quick note; it is, of course, possible to import data from other formats. If you need to here are a couple of tutorials on how to read data from SPSS, Stata, and SAS:

Now that we have some example data, we can go on by adding a column first using base R and, then, by using add_column(). After that, we’ll also add multiple columns using both methods. As you may understand, appending an empty column is a task done, more or less, the same way as when we add a column to a dataframe in R.

How to Add an Empty Column to a Dataframe in R in Two Ways

In this section, we will look at two methods adding empty columns to an R dataframe. First, we’ll use base R:

1 Adding a Column using Base R

Here’s how to insert an empty column (i.e., containing missing values) to the dataframe:

dataf['new_col'] <- NA

It was quite simple, we just added the new column name within brackets (‘new_col’) and then assigned NA to this. Here’s the dataframe with the added empty column:

Added, empty, column marked with yellow in the R dataframe
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Newly added, and empty, column to the dataframe in R

In the next example, we will add NA to a new column using tibble’s add_column().  If you need to, you can also generate a sequence of numbers in R e.g. using the rep() function.

2 Inserting a Column using add_column()

To add an empty column (i.e., NA) to a dataframe in R using add_column() we just do as follows:

library(tibble)
library(dplyr)

dataf <- dataf %>%
  add_column(Empty_Col = NA)
head(dataf)

In the example above, we just added the empty column at “the end” of the dataframe. Importantly, in the code above we added the empty column to the original dataframe. If you, on the other hand, want to add a column and create a new dataframe you can change the code. For instance, changing dataf to dataf2 to the left of the <- would do the trick.

Empty column added to the dataframe using add_column
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Dataframe with added empty column

Noteworthy, there are two interesting arguments that we can work with if we want to insert the new column at a specific location. 

These two arguments are .before and .after. If we, for example, want to add an empty column after the column named “Mean” we add the .after argument like this:

dataf <- dataf %>%
  # Creating an empty column:
  add_column(Empty_Col2 = NA, .after="Mean")
head(dataf)
Added new empty column after specific column in Dataframe R
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Added the empty column after the “Mean” column

Finally, if we don’t want to work with dplyr we can add the dataframe as the first argument:

library(tibble)
library(dplyr)

dataf <- add_column(dataf, Empty_Col = NA)

Now that you have added an empty column to the dataframe, you might want to create dummy variables in R (e.g., if you have categorical variables).

How to Add Multiple Columns to a Dataframe

In this section, that is similar to the first section, we will be adding many columns to a dataframe in R. Specifically, we will add 2 empty columns using base R and the add_column() (tibble). As you might understand, after you have had a look at the examples, inserting more columns is just repeating or adding to the code. Note, we use the same example dataframe as in the previous example.

1 Adding Multiple Columns with R Base

Here’s how to add multiple empty columns with R base:

dataf['new_col1'] <- NA
dataf['new_col2'] <- NA

As in the previous example, we used the brackets and set the new column name between them (i.e., ‘new_col1’). The second empty column was added the same way but with an unique name. Here’s how to dataframe look like with the two empty columns added:

Two empty columns added to the dataframe
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2 Adding Multiple Columns with the add_column() function

Here’s how to add multiple columns using add_column():

dataf &lt;- dataf %>%
  add_column(Empty_Col1 = NA,
             Empty_Col2 = NA)

Again, we can decide where in the dataframe we want to add the empty columns by using either the .after or .before arguments (see the example for adding an empty column). If you need to add 3 or 5 (or more) columns you just add the column names for them and what they should contain.(e.g., NA for empty). If you want to create an enviornment so that other people can test, run, and use your code the exact same way you could, you coud use binder and R for reproducible code.

Empty Column added to the Dataframe in R
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Empty column added to the Dataframe

Note, whether you add one or multiple empty columns you need to make sure that you use a new, and unique, column name for each column. If you don’t, you might overwrite your data. Note, you could also add new columns to the dataframe creating data using the repeat and replicate functions in R.

Conclusion

In this post, we learned how to add empty columns to a dataframe in R. Specifically, we used base R and tibble (add_column()). First, we added a single empty column by simply assigning NA to it. Second, we then used the function add_column() with the new column name as an argument and NA as input. Finally, we used the two methods to also learn how to add multiple columns to the dataframe.

Hope you enjoyed the R tutorial and please leave a comment below if there is something you want to be covered, in general on the blog, as well in this blog post. Finally, please share the post if you learned something new!

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