获取 R 编程中因子的级别数 – nlevels()函数

R 语言中的nlevels()函数用于获取因子的级别数。

Syntax: nlevels(x)

Parameters:
x: Factor Object

示例 1：

# R program to get the number
# of levels of a factor
  
# Creating a factor
x <- gl(3, 2)
x
  
# Calling nlevels() function
# to get the number of levels
nlevels(x)

输出：

[1] 1 1 2 2 3 3
Levels: 1 2 3
[1] 3

示例 2：

# R program to get the number
# of levels of a factor
  
# Creating a factor
gender <- factor(c("female", "male", "male", "female")); 
gender
  
# Calling nlevels() function
# to get the number of levels
nlevels(gender)

输出：

[1] female male   male   female
Levels: female male
[1] 2