R gl() Function

The gl() function in R is a convenient way to generate factors with a specified pattern of levels. It stands for “generate levels”, and it is often used in creating experimental designs or during data analysis for categorizing data into groups.

Syntax

gl(n, k, length = n*k, labels = seq_len(n), ordered = FALSE)

Parameters

  1. n: It is an integer giving the number of levels.
  2. k: It is an integer giving the number of replications.
  3. length: It is an integer giving the length of the result.
  4. labels: It is an optional vector of labels for the resulting factor levels.
  5. ordered: It is a logical argument indicating whether the result should be ordered.

Example 1: Basic usage

Using gl() function

fact <- gl(3, 2, labels = c("Erlich", "Richard", "Gilfoyle"))

fact

Output

[1] Erlich Erlich Richard Richard Gilfoyle Gilfoyle
Levels: Erlich Richard Gilfoyle

Example 2: Specify labels

data <- gl(3, 4, 10, label = letters[1:12])
data

app <- gl(3, 4, 10, label = letters[1:12], ordered = T)
app

Output

[1] a a a a b b b b c c
Levels: a b c d e f g h i j k l

[1] a a a a b b b b c c
Levels: a < b < c < d < e < f < g < h < i < j < k < l

Example 3: Changing the order of levels

Changing the order of levels

data <- c("Erlich", "Richard", "Gilfoyle", "Gilfoyle", "Erlich", "Richard")

factor_data <- factor(data)
factor_data

ordered_data <- factor(factor_data, levels = c("Richard", "Erlich", "Gilfoyle"))
ordered_data

Output

[1] Erlich Richard Gilfoyle Gilfoyle Erlich Richard
Levels: Erlich Gilfoyle Richard

[1] Erlich Richard Gilfoyle Gilfoyle Erlich Richard
Levels: Richard Erlich Gilfoyle

That’s it.

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