[R] Odp: Replace selected columns of a dataframe with NA

[Petr PIKAL]

Hi

> 
> I am using the following command to replace all the missing values and
> assorted typos in a dataframe with NA:
> 
> mydata[mydata>80]=NA
> 
> The problem is that the first column contains values which should be
> more than 80, so really I want to do it just for
> mydata[,2:length(mydata)]
> 
> I can't seem to re-write the code to fit:
> 
> mydata[,2:length(mydata)>80]=NA # no error message, but doesn't work-
> doesn't do anything, it would seem

mydata[,-1][mydata[,-1]>80]<-NA

shall do what you want

Regards
Petr

> 
> I realise I can just keep the first column somewhere safe and copy it
> back again when I'm done, but I wondered if there was a more elegant
> solution, which would be much more important, if say I just wanted to
> replace the odd columns, or something like that.
> 
> I found this code on the internet too:
> 
> idx <- which(foo>80, arr.ind=TRUE)
> foo[idx[1], idx[2]] <- NA
> 
> But I can't seem to rewrite that either, for the same reason
> 
> Many thanks!
> 
> Chris Beeley
> Institute of Mental Health
> 
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