Remove empty levels in subset

Hi,

Hi,

I have exactly the same question (how to remove empty levels in my subset),
but in my case the factor command does not work, because my dataframe is not
atomic

Try this:

test2$a <- factor(test2$a)

R gives me the error message:

Error in sort.list(y) : 'x' must be atomic for 'sort.list'
Have you called 'sort' on a list?

Do you have advice?

I have two pieces of advice.

1. Don't try to use factor() on your entire data frame, but only on a
single column at a time, as shown in the example you included.

2. Provide an example of your data using something like
dput(head(mydata, 10)) so we can offer actual working code.

Sarah

Sarah Goslee
http://www.functionaldiversity.org

Thank you very much. The advice I followed (and which, for some reason, I do
not see here right now) was to use 'droplevels'. I needed the command for
several variables at the same time, so this was very convenient.

Hello,

Have you tried 'droplevels':
test <-data.frame(a=as.factor(rep(c("f1","f2","f3"),10)),b=rep(c(1,2,3),10)) 
test2 <- subset(test,test$a=="f1") 
summary(test2)
  a            b    
 f1:10   Min.   :1  
 f2: 0   1st Qu.:1  
 f3: 0   Median :1  
         Mean   :1  
         3rd Qu.:1  
         Max.   :1  
test3<-droplevels(test2)
summary(test3)
  a            b    
 f1:10   Min.   :1  
         1st Qu.:1  
         Median :1  
         Mean   :1  
         3rd Qu.:1  
         Max.   :1  
A.K.

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