Unable to create a for loop to convert multiple varialbe into as.factor-CodePudding

I am trying to write a for loop in r to convert multiple variables with similar character pattern in r to as.factor.

Below is the function I wrote, R runs the code, does not show any error, but does not give the desired output. There is a logical error, can someone help me correct this error?

for (i in grep(pattern = "hml35_", x=tanre)) 
{
    tanre$i<-as.factor(tanre$i)
}

CodePudding user response：

Assuming the grep pattern returns the column names, you need to change the syntax:

for (i in grep(pattern = "hml35_", x=tanre)) 
{
    tanre[[i]]<-as.factor(tanre[[i]])
}

R is expecting the literal column name when you use the $ operator.

Edit: You could use lapply here instead of a loop. I would also have a look at using mutate across.

CodePudding user response：

A solution with tidyverse

library(tidyverse)

tanre %>%
  mutate_at(vars(contains("hml35_")), as.factor)