将data.frame列格式从字符转换为因子 [英] convert data.frame column format from character to factor

问题描述

我用R语言编程。我想将我的data.frame对象（ mydf ）的某些列的格式（类）从 charactor 更改为 factor 。我不想这样做，当我通过 read.table（）函数读取文本文件。任何帮助将不胜感激。

I am programming in R language. I would like to change the format (class) of some columns of my data.frame object (mydf) from charactor to factor. I don't want to do this when I'm reading the text file by read.table() function. Any help would be appreciated.

推荐答案

欢迎来到R的世界。

mtcars  #look at this built in data set
str(mtcars) #allows you to see the classes of the variables (all numeric)

#one approach it to index with the $ sign and the as.factor function
mtcars$am <- as.factor(mtcars$am)
#another approach
mtcars[, 'cyl'] <- as.factor(mtcars[, 'cyl'])
str(mtcars)  # now look at the classes

这也适用于字符，日期，整数和其他类。

This also works for character, dates, integers and other classes

建议您查看这两个网站：

R参考手册：
http://cran.r-project.org/manuals.html

R参考卡： http：//cran.r-project .org / doc / contrib / Short-refcard.pdf

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