R语言 获取一个因子的水平数 – nlevels()函数

R语言中的 nlevels() 函数是用来获取一个因子的级数的。

语法： nlevels(x)

参数：

x： 因子对象

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

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