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I've got a list of dataframes and am trying to change the first colname using the lapply method

frames<-lapply(frames,function(x){ colnames(frames[[x]])[1]<-"date"})

is returning the error 

Error in `*tmp*`[[x]] : invalid subscript type 'list'

I am not sure why it would produce this error as my understanding is that this should apply 

colname[1]<-"date"

to every data frame in the list

If anyone can tell me the root of this error I would be very grateful!

user124123
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1 Answers1

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You do not need to reference the frames list inside of lapply. Your function treats x as an element in the list, frames. Try this:

frames <- lapply(frames, function(x) { colnames(x)[1] <- "date"; return(x) })

Rich Scriven
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ialm
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  • @RichardScriven I like to be explicit :) – ialm Oct 21 '14 at 16:56
  • Ok sorry, I rolled it back. `return` slows things down so I don't really use it unless necessary – Rich Scriven Oct 21 '14 at 16:57
  • @RichardScriven Oh, I didn't know that `return` slows down code performance. I may have to refrain from using `return` in my code... do you know why it slows things down? (Sorry - off topic, but I'm interested) – ialm Oct 21 '14 at 16:59
  • Here's a good read about that http://stackoverflow.com/questions/11738823/explicitly-calling-return-in-a-function-or-not. It's really just a matter of personal preference – Rich Scriven Oct 21 '14 at 17:04