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

我想将 data.frame 对象 (mydf) 的某些列的格式(类)从 charactor 更改为 factor.

I would like to change the format (class) of some columns of my data.frame object (mydf) from charactor to factor.

当我通过 read.table() 函数读取文本文件时，我不想这样做.

I don't want to do this when I'm reading the text file by read.table() function.

任何帮助将不胜感激.

推荐答案

您好，欢迎来到 R 的世界.

Hi welcome to the world of R.

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

由于您是 R 的新手，我建议您查看以下两个网站:

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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