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In R, there are several methods for converting a character to a numeric value. The most common approach is to use the as.numeric() function, which takes a character input and returns the numerical equivalent. Other options include using the as.integer() or as.double() functions, depending on the desired output type.
Examples of converting a character to numeric in R include converting a string of numbers, such as “123”, to its numeric value of 123, or converting a string of letters, such as “ABC”, to its ASCII numerical representation. Another example is converting a character vector containing multiple elements, such as “1”, “2”, and “3”, to a numeric vector of 1, 2, and 3. It is important to note that if the character input cannot be converted to a numeric value, R will return an error.
Convert Character to Numeric in R (With Examples)
We can use the following syntax to convert a character vector to a numeric vector in R:
numeric_vector <- as.numeric(character_vector)
This tutorial provides several examples of how to use this function in practice.
Example 1: Convert a Vector from Character to Numeric
The following code shows how to convert a character vector to a numeric vector:
#create character vector
chars <- c('12', '14', '19', '22', '26')
#convert character vector to numeric vector
numbers <- as.numeric(chars)
#view numeric vector
numbers
[1] 12 14 19 22 26
#confirm class of numeric vector
class(numbers)
[1] "numeric"
Example 2: Convert a Column from Character to Numeric
The following code shows how to convert a specific column in a data frame from character to numeric:
#create data frame
df <- data.frame(a = c('12', '14', '19', '22', '26'),
b = c(28, 34, 35, 36, 40))
#convert column 'a' from character to numeric
df$a <- as.numeric(df$a)
#view new data frame
df
a b
1 12 28
2 14 34
3 19 35
4 22 36
5 26 40
#confirm class of numeric vector
class(df$a)
[1] "numeric"
Example 3: Convert Several Columns from Character to Numeric
The following code shows how to convert all character columns in a data frame from character to numeric:
#create data frame
df <- data.frame(a = c('12', '14', '19', '22', '26'),
b = c('28', '34', '35', '36', '40'),
c = as.factor(c(1, 2, 3, 4, 5)),
d = c(45, 56, 54, 57, 59))
#display classes of each column
sapply(df, class)
a b c d
"character" "character" "factor" "numeric"
#identify all character columns
chars <- sapply(df, is.character)
#convert all character columns to numeric
df[ , chars] <- as.data.frame(apply(df[ , chars], 2, as.numeric))
#display classes of each column
sapply(df, class)
a b c d
"numeric" "numeric" "factor" "numeric"
This code made the following changes to the data frame columns:
- Column a: From character to numeric
- Column b: From character to numeric
- Column c: Unchanged (since it was a factor)
- Column d: Unchanged (since it was already numeric)
By using the and functions, we were able to convert only the character columns to numeric columns and leave all other columns unchanged.