[R] Seeing negative numbers to zero

[David Winsemius]

On Aug 7, 2009, at 4:29 PM, DebbieMB wrote:

>
> Hi,
>
> I am also new to R and I have a related question.  I am trying to set
> negative values in a single column of a dataframe to zero and I  
> can't seem
> to do it.
>
> I have tried:
> KN1<-subset(KN,select=c(5))
> # Here I am selecting the column of the dataframe KN1 and assigning  
> it the
> name KN2 - this step works
> KN2<-ifelse(KN1<=0,0,KN1)
> # Here I am trying to set negative numbers to zero and leave all other
> numbers the same - this doesn't work

KN1 is probably still a dataframe (albeit with only one column)  and  
you really meant to be working on that column  instead of the whole  
dataframey-listy-thing with all of its attached attributes and  
classes. You need to refer to the name of the column, let's say its  
"col1"

KN2 <- ifelse(KN1$col1<=0,0,KN1$col1)

>
> Any help would be appreciated.
>
> Thanks,
> Debbie
>
>
> tonybreyal wrote:
>>
>> see ?ifelse
>>
>> you didn't specify what happens if a value is exactly zero in the  
>> dataset
>> and so i've just bundled it in with the negative case:
>>
>> x <- rnorm(20, 0, 1)
>> y<-ifelse(x<=0, 10, 5)
>>
>> HTH,
>> Tony Breyal
>>
>>
>> cmga20 wrote:
>>>
>>> Hi i am very new to R and I have been trying to change each  
>>> individual
>>> piece of data in a data set to 10 if it is below 0 and 5 if it is  
>>> above
>>> 0. I know this sounds very easy but i am struggling!!
>>>
>>
>>
>
> -- 
> View this message in context: http://www.nabble.com/For-loop-for-distinguishing-negative-numbers-tp24499872p24870518.html
> Sent from the R help mailing list archive at Nabble.com.
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT