在R和summary（）函数中创建因子级别

Question

所以， 我正在学习R. 我在这里关注本教程：https://www.datacamp.com/courses/introduction-to-r/chapter-4-factors?ex=4

这就是我投入的内容：

survey_vector <- c("M","F","F","M","M")
factor_survey_vector <- factor(survey_vector)

# Your code here
levels(factor_survey_vector) <- c("Female","Male")

factor_survey_vector
summary(factor_survey_vector)

这就是它在R

中提示的内容

> factor_survey_vector
[1] Male   Female Female Male   Male  
Levels: Female Male
> summary(factor_survey_vector)
Female   Male 
     2      3 

虽然我理解factor_survey_vector的提示，但我不理解summary(factor_survey_vector)的提示。 R怎么知道，有2个女性和3个男性？我只将矢量c("Female","Male")指定给levels(factor_survey_vector)。它如何解释，每个M是一个男性，每个F一个女性？我想我在这里监督一些非常微不足道的事情？！

Answer 1

您可以使用str()查看基础结构：

> survey_vector <- c("M","F","F","M","M")
> factor_survey_vector <- factor(survey_vector)
> 
> 
> str(factor_survey_vector)
 Factor w/ 2 levels "F","M": 2 1 1 2 2

所以factor_survey_vector是2 1 1 2 2，等级1是＆＃34; F＆＃34;和2级＆＃34; M＆＃34;

> levels(factor_survey_vector) <- c("Female","Male")
> str(factor_survey_vector)
 Factor w/ 2 levels "Female","Male": 2 1 1 2 2

这里唯一的区别是关卡标签已经改变。现在1是女性，2是男性。