[R] Looping through data sets to change column from character to numeric

["Dénes TÓTH"]

Sorry, I was wrong. Of course you can assign a variable to itself, but it
does not make much sense...
What you misunderstood was that in the assignment you assign the data
frame (e.g. "df1") to itself. You do not modify the frame object which
remains a character string.


>
> The problem is that you can not assign a variable to itself.
>
> rm(list=ls())
> df1 <- data.frame(ResultValue=as.character(1:5))
> df2 <- data.frame(ResultValue=as.character(1:10))
> frames = ls()
> for (frame in frames){
>      temp <- get(frame)
>      temp[,"ResultValue"] = as.numeric(temp[,"ResultValue"])
>      assign(frame,temp)
> }
>
> HTH,
>   Denes
>
>
>
>> Greetings to all --
>>
>> I am having a silly problem that I just can't solve.  Someone has given
>> me
>> an .RData file will hundreds of data frames.  Each data frame has a
>> column
>> named ResultValue, currently character when it should be numeric.  I
>> want
>> to
>> loop through all of the data frames to change the variable to numeric,
>> but
>> I
>> cannot figure out how to do it. My best guess was along the lines of:
>>
>> frames = ls()
>> for (frame in frames){
>>      assign(frame, get(frame), .GlobalEnv)
>>      frame[,"ResultValue"] = as.numeric(frame[,"ResultValue"])
>>      }
>>
>> It doesn't work.  After the assign() the frame object remains the
>> character
>> name of the dataframe I am trying to change.  If I do the following, the
>> TEST object comes out just fine.
>>
>> frames = ls()
>> for (frame in frames){
>>      assign("TEST", get(frame), .GlobalEnv)
>>      TEST[,"ResultValue"] = as.numeric(TEST[,"ResultValue"])
>>      }
>>
>> Seems like it should be simple, but I am misunderstanding something and
>> not
>> following the logic.  Any insight?
>>
>> Thanks,
>>
>> Sarah
>>
>> 	[[alternative HTML version deleted]]
>>
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>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>