Label Encoder functionality in R?

Question

In python, scikit has a great function called LabelEncoder that maps categorical levels (strings) to integer representation.

Is there anything in R to do this?

Answer 1

Create your vector of data:

colors <- c("red", "red", "blue", "green")

Create a factor:

factors <- factor(colors)

Convert the factor to numbers:

as.numeric(factors)

Output: (note that this is in alphabetical order)

# [1] 3 3 1 2

You can also set a custom numbering system: (note that the output now follows the "rainbow color order" that I defined)

rainbow <- c("red","orange","yellow","green","blue","purple")
ordered <- factor(colors, levels = rainbow)
as.numeric(ordered)
# [1] 1 1 5 4

See ?factor.