How to Convert a Character to Numeric in R

Basic R Syntax:

x_num <- as.numeric(x)

Do you need more explanations? In the following article, I’ll provide you with all important information for the conversion of character vectors to numeric in R.

Example: Convert Character to Numeric in R

Before we can dive into the transformation of a character variable to numeric, we need to create an example character in R. Consider the following vector:

set.seed(55555)                                              # Set seed
x <- as.character(sample(c(2, 5, 7, 8), 50, replace = TRUE)) # Example character vector

Our string consists of the four character values 2, 5, 7 & 8:

x                                                            # Print example vector to R console

How to Convert Character to Numeric Example Vector

Graphic 1: Example Character String Printed to the RStudio Console

Now, we can continue with the important part – How to convert this character string to numeric?

No Problem:

x_num <- as.numeric(x)                                 # Convert string to numeric in R
x_num                                                  # Print converted x to the console
# 8 7 5 8 2 5 2 5 2 7 7 7 7...

That’s basically how to apply the as.numeric function in R. However, if you need some more explanations for the conversion of data types, you might have a look at the following video of my YouTube channel. In the video, I’m explaining how to convert character and factors to numeric in R:

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Convert All Characters of a Data Frame to Numeric

As you have seen, to convert a vector or variable with the character class to numeric is no problem. However, sometimes it makes sense to change all character columns of a data frame or matrix to numeric.

Consider the following R data.frame:

x1 <- c("5", "2", "7", "5")                            # Character
x2 <- c("77", "23", "84", "11")                        # Another character
x3 <- as.factor(c("4", "1", "1", "8"))                 # Factor
x4 <- c(3, 3, 9, 7)                                    # Numeric
 
data <- data.frame(x1, x2, x3, x4,                     # Create data frame
                   stringsAsFactors = FALSE)
sapply(data, class)                                    # Print classes of all colums
#          x1          x2          x3          x4 
# "character" "character"    "factor"   "numeric"

Data Frame with Character, Factor & Numeric Columns

Table 1: Example Data Frame with Different Variable Classes

With the following R code, you are able to recode all variables – no matter which variable class – of a data frame to numeric:

data_num <- as.data.frame(apply(data, 2, as.numeric))  # Convert all variable types to numeric
sapply(data_num, class)                                # Print classes of all colums
#        x1        x2        x3        x4 
# "numeric" "numeric" "numeric" "numeric"

However, in many situations it is better to convert only character columns to numeric (i.e. not column X3, since this column should be kept as factor). You could do that with the following code in R:

char_columns <- sapply(data, is.character)             # Identify character columns
data_chars_as_num <- data                              # Replicate data
data_chars_as_num[ , char_columns] <- as.data.frame(   # Recode characters as numeric
  apply(data_chars_as_num[ , char_columns], 2, as.numeric))
sapply(data_chars_as_num, class)                       # Print classes of all colums
#        x1        x2        x3        x4 
# "numeric" "numeric"  "factor" "numeric"

Example Video: How to Change Variable Types

Further examples needed? Have a look at the following R Programming tutorial of the YouTube Channel LearnR. The speaker discusses different data transformations from one data class to another.

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Don
August 5, 2020 1:14 pm

I spent all afternoon scrolling through Stack Overflow trying to figure out how to do this. Once I found it on your site, it took 5 minutes. Thank you!!

Reply
- Joachim
  August 17, 2020 6:54 am
  
  Wow that’s an amazing feedback! Thanks Don 🙂
  
  Reply
Don
August 5, 2020 2:44 pm

How can I keep this from converting my rowname chars to numeric?

Reply
- Joachim
  August 17, 2020 7:01 am
  
  Hey Don,
  
  You may convert only a subset of your data frame to numeric. Have a look here for more info.
  
  Regards,
  
  Joachim
  
  Reply
Larry Cordell
September 2, 2020 5:37 pm

I just had 3 variables in a 17-variable data set to convert from character to numeric. This didn’t help at all I’m afraid.

Reply
- Joachim
  September 3, 2020 6:15 am
  
  Hi Larry,
  
  Could you explain why it didn’t help? Maybe we can figure out a solution for your problem 🙂
  
  Regards,
  
  Joachim
  
  Reply
Vaibhav Datta
September 12, 2020 7:29 pm

Hi. How to stop getting the “Coerced to NA” warning?

Reply
- Joachim
  September 14, 2020 6:02 am
  
  Hi Vaibhav,
  
  This typically happens when your characters are not representing numbers (e.g. “5!”, “1,55”, “seven”). Have you checked how your data is formatted before converting it?
  
  Regards,
  
  Joachim
  
  Reply
Busola
September 15, 2020 6:17 pm

I have factors with levels and labels; how do I convert them to numeric

Reply
- Joachim
  September 16, 2020 5:49 am
  
  Hey Busola,
  
  I have another article on converting factors to numeric: https://statisticsglobe.com/how-to-convert-a-factor-to-numeric-in-r/
  
  Let me know if this solved your problem.
  
  Regards,
  
  Joachim
  
  Reply
SHRINIVAS
November 28, 2020 6:29 am

Hello Jo

I have a data frame which is all in text. Recent Kaggle competition (https://www.kaggle.com/c/kaggle-survey-2020)

While converting from Character to Numeric, I am having problem of NA Coercion

So I saw your Youtube Video and then looked up the above tutorial. Here a2 is the original data set of Kaggle imported as Header F.

However, I am still getting NA coercion. Please help

data <- data.frame(a2$V2, a2$V3, a2$V4, a2$V5, stringsAsFactors = FALSE)
sapply(data, class)

a2.V2 a2.V3 a2.V4 a2.V5
"numeric" "character" "character" "character"

data1 sapply(data_num, class)
Error in lapply(X = X, FUN = FUN, …) : object ‘data_num’ not found

> sapply(data1, class)

a2.V2 a2.V3 a2.V4 a2.V5
“numeric” “numeric” “numeric” “numeric”

> head(data1, 6)

a2.V2 a2.V3 a2.V4 a2.V5
1 NA NA NA NA
2 NA NA NA NA
3 NA NA NA NA
4 NA NA NA NA
5 NA NA NA NA
6 NA NA NA NA
>
> data sapply(data, class)
a2.V2 a2.V3 a2.V4 a2.V5
“numeric” “character” “character” “character”
> data1 sapply(data_num, class)
Error in lapply(X = X, FUN = FUN, …) : object ‘data_num’ not found
> sapply(data1, class)
a2.V2 a2.V3 a2.V4 a2.V5
“numeric” “numeric” “numeric” “numeric”
> head(data1,6)
a2.V2 a2.V3 a2.V4 a2.V5
1 NA NA NA NA
2 NA NA NA NA
3 NA NA NA NA
4 NA NA NA NA
5 NA NA NA NA
6 NA NA NA NA
>

Reply
- Joachim
  November 28, 2020 8:16 am
  
  Hey Shrinivas,
  
  I hope you doing fine?
  
  Regarding your question, I would have a look at two things:
  
  1) The NA coercion problem usually appears, because the character numbers are not formatted properly. More info: https://statisticsglobe.com/warning-message-nas-introduced-by-coercion-in-r
  
  2) It seems like you are trying to use a data frame that does not exist in your workspace. For that reason you get the error “object ‘data_num’ not found”. Please check if this data frame really exists.
  
  I hope that helps!
  
  Joachim
  
  Reply
Leo
January 4, 2021 2:59 pm

Dear Joachim,

thanks for your great videos and website. This time however, I wasn’t able to solve my problem as its more specific but I hope you can bring more light into this:
I have a given column (CV that I want to test in a ANCOVA) in my data set which contains numbers similar to this “-,038040659585351” and its structure is character by default. Now nothing has worked to convert this into numeric. It either got changed into NAs or a whole lot of different numbers.

Do you happen to have an idea to convert it into numeric?

Many thanks in advance!

Leo

Reply
- Joachim
  January 5, 2021 6:47 am
  
  Hey Leo,
  
  Thanks a lot for the nice feedback! I’m happy to hear that you like my content 🙂
  
  Regarding your question, I would try the following:
  
  Step 1) Make sure that the column is a character (not a factor) as explained here: https://statisticsglobe.com/convert-factor-to-character-in-r
  
  Step 2) Use the gsub function to replace all non-numeric symbols and letters in your data. This depends a bit on the exact structure of your data, however, you can find a detailed tutorial here: https://statisticsglobe.com/sub-gsub-r-function-example
  
  Step 3) Convert your column to numeric as shown in this tutorial.
  
  Let me know if it worked 🙂
  
  Joachim
  
  Reply
Elisa
January 16, 2021 10:12 pm

Hi Joachim,

I really appreciate your examples. I am struggling to figure out how to convert a character field with the values Y or N to a Numeric where the Y=1 and the N=0. Similarly, I need to understand how to change Education Levels e.g., Sixth grade to 6, 9th grade to 9th, High School Diploma to 12, … PhD to 22 etc.

Any help you can provide with this is much appreciated.

Thanks again.

Reply
- Joachim
  January 18, 2021 7:23 am
  
  Hey Elisa,
  
  Thank you for the nice feedback!
  
  Regarding your question, please follow these steps:
  
  1) Make sure that your column has the character class: https://statisticsglobe.com/convert-factor-to-character-in-r
  
  2) Replace your values: https://statisticsglobe.com/r-replace-value-of-data-frame-variable-dplyr-package
  
  3) Convert your column to numeric as shown in this tutorial.
  
  Regards,
  
  Joachim
  
  Reply