CODEWITHSUNDEEP
r
Bert Maier
Bert Maier

Reputation: 71

Rename columns based on pattern R

I would like to rename multiple columns in a data frame with a function.

Data frame

nameAXX = c("car1", "car2", "car2", "car2", "car3", "car1") 
brand = c("b1", "b2", "b2", "b2", "b3", "b1")
productionAXX = c(10, 10, 10, 40, 10, 5) 
df = data.frame(brand, nameAXX, productionAXX)

The loop itself works but not if I wrap it in a function and call it.

replaceColNamePattern <- function(df, pattern, replace){
  for (name in colnames(df)){
    if (regexpr(pattern, name) > 0){
      names(df)[names(df)==name] <- gsub(pattern, replace, name)
    }
  }
}

Call function

replaceColNamePattern(adf, "AXX", "")

Is it not possible to rename the column within a function?

Upvotes: 1

Views: 1909

Answers (1)

thothal
thothal

Reputation: 20369

Besides the excellent answers of akrun et. alii, the reason why your code is not working as intended is because you change the name of df in the scope of the function (and only there). You would need to return df and assign it back to the original variable:

replaceColNamePattern2 <- function(df, pattern, replace){
   names(df) <- gsub(pattern, replace, names(df))
   df
}

(df <- replaceColNamePattern2(df, "AXX", ""))
#   brand name production
# 1    b1 car1         10
# 2    b2 car2         10
# 3    b2 car2         10
# 4    b2 car2         40
# 5    b3 car3         10
# 6    b1 car1          5

Upvotes: 2

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