Table of Contents
Using the dplyr package, it is possible to convert multiple columns to numeric by utilizing the mutate() and as.numeric() functions. The mutate() function allows for the modification of existing columns in a data frame, and the as.numeric() function converts the columns to a numeric data type. This can be done using a single line of code for each column, or multiple columns can be converted at the same time using the select() and mutate_at() functions. This is a useful tool for quickly changing the data type of columns in a data frame.
You can use the following methods to convert multiple columns to numeric using the package:
Method 1: Convert Specific Columns to Numeric
library(dplyr) df %>% mutate_at(c('col1', 'col2'), as.numeric)
Method 2: Convert All Character Columns to Numeric
library(dplyr) df %>% mutate_if(is.character, as.numeric)
The following examples show how to use each method in practice.
Example 1: Convert Specific Columns to Numeric
Suppose we have the following data frame in R:
#create data frame
df <- data.frame(team=c('A', 'B', 'C', 'D', 'E'),
position=c('G', 'G', 'G', 'F', 'F'),
assists=c('33', '28', '31', '39', '34'),
rebounds=c('30', '28', '24', '24', '28'))
#view structure of data frame
str(df)
'data.frame': 5 obs. of 4 variables:
$ team : chr "A" "B" "C" "D" ...
$ position: chr "G" "G" "G" "F" ...
$ assists : chr "33" "28" "31" "39" ...
$ rebounds: chr "30" "28" "24" "24" ...
We can see that every column in the data frame is currently a character.
To convert just the assists and rebounds columns to numeric, we can use the following syntax:
library(dplyr) #convert assists and rebounds columns to numeric df <- df %>% mutate_at(c('assists', 'rebounds'), as.numeric) #view structure of updated data frame str(df) 'data.frame': 5 obs. of 4 variables: $ team : chr "A" "B" "C" "D" ... $ position: chr "G" "G" "G" "F" ... $ assists : num 33 28 31 39 34 $ rebounds: num 30 28 24 24 28
We can see that the assists and rebounds columns are now both numeric.
Example 2: Convert All Character Columns to Numeric
Suppose we have the following data frame in R:
#create data frame
df <- data.frame(ranking=factor(c(1, 4, 3, 2, 5)),
assists=c('12', '10', '8', '11', '15'),
points=c('33', '28', '31', '39', '34'),
rebounds=c('30', '28', '24', '24', '28'))
#view structure of data frame
str(df)
'data.frame': 5 obs. of 4 variables:
$ ranking : Factor w/ 5 levels "1","2","3","4",..: 1 4 3 2 5
$ assists : chr "12" "10" "8" "11" ...
$ points : chr "33" "28" "31" "39" ...
$ rebounds: chr "30" "28" "24" "24" ...
We can see that three of the columns in the data frame are character columns.
library(dplyr) #convert all character columns to numeric df <- df %>% mutate_if(is.character, as.numeric) #view structure of updated data frame str(df) 'data.frame': 5 obs. of 4 variables: $ ranking : Factor w/ 5 levels "1","2","3","4",..: 1 4 3 2 5 $ assists : num 12 10 8 11 15 $ points : num 33 28 31 39 34 $ rebounds: num 30 28 24 24 28
We can see that all of the character columns are now numeric.
Note: Refer to the for a complete explanation of the mutate_at and mutate_if functions.
The following tutorials explain how to perform other common operations in R: