[R] add specific fields in for loop

[Kai Yang]

Hello Rui,
Yes, it should be the one I want. I modified the code as:

for(i in grep("data", names(df))) {
  try2.un$ab2 <-
    ifelse(grepl("ab2",  [i]),   [i], NA)
}

But I got error message: 
Error: unexpected '[' in:
"  try2.un$ab2 <-
    ifelse(grepl("ab2",["

I think I use [i] in a wrong way. Do you have any suggestion?
Thanks,
Kai   On Tuesday, November 15, 2022 at 10:54:08 AM PST, Rui Barradas <ruipbarradas using sapo.pt> wrote:  
 
 Às 16:18 de 15/11/2022, Kai Yang via R-help escreveu:
> Hi Team,
> I can write a for loop like this:
> for (i in columns(df)){
>    ......
> }
> 
> But it will working on all column in dataframe df. If I want to work on some of specific fields (say: the fields' name content 'date'), how should I modify the for loop? I changed the code below, but it doesn't work.
> for (i in columns(df) %in% 'date' ){
>    .....
> }
> 
> 
> Thank you,
> Kai
> 
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> 
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Hello,

Something like this?


for(i in grep("date", names(df))) {
  #
}


Hope this helps,

Rui Barradas

  
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