In this tutorial, we will look at how to convert a character type field (for example, a vector or a dataframe column) to a numeric type in R.
How to convert character type data to numeric in R?
You can use the as.numeric() function in R to convert character type to numeric type in R. Pass the field (for example, a vector) as an argument to the function. The following is the syntax –
as.numeric(x)
If you pass a vector to the above function, it returns a vector with each value in numeric type.
Examples
Let’s now look at some examples of using the as.numeric() function in R.
Convert character type vector to numeric type vector
Let’s create a vector with numbers as character type values and then apply the as.numeric() function.
# create a vector
vec <- c('1', '2', '3', '4')
# convert to numeric
vec <- as.numeric(vec)
# display the vector
print(vec)
# display vector's type
print(class(vec))
Output:
[1] 1 2 3 4 [1] "numeric"
The resulting vector has numeric values.
Note that this method will not work if the character type values cannot be converted to numeric type. For example, “a”
# create a vector
vec <- c('a', 'b', 'c', 'd')
# convert to numeric
vec <- as.numeric(vec)
# display the vector
print(vec)
# display vector's type
print(class(vec))
Output:
Warning message in eval(expr, envir, enclos): “NAs introduced by coercion” [1] NA NA NA NA [1] "numeric"
We get a vector of NA values and a warning. This is because the original values from the vector cannot be converted to numeric.
Convert character type dataframe column to numeric type
You can also use the as.numeric() function to change the data type of a dataframe column in R to numeric.
Let’s look at an example.
First, we will create a dataframe with the height and weight information of some students in a university.
# create a data frame
df <- data.frame(
"Name"= c("Tim", "Hasan", "Vlad", "Maria"),
"Height"= c("168", "174", "162", "158"),
"Weight"= c(73, 81, 65, 55)
)
# display the dataframe
print(df)
Output:
Name Height Weight 1 Tim 168 73 2 Hasan 174 81 3 Vlad 162 65 4 Maria 158 55
You can see that the “Height” column in the above dataframe is of character type. Let’s change its type to numeric type using the as.numeric() function.
# convert "Height" column to numeric type df$Height <- as.numeric(df$Height) # display "Height" column's type print(class(df$Height))
Output:
[1] "numeric"
You can see that the “Height” column is now of numeric type.
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