[R] unique: factor to string

[David Winsemius]

On Jan 18, 2010, at 10:05 AM, Markus Mühlbacher wrote:

> Hi community,
>
> I want to count the occurrence of values within a dataframe.
> data$names is a list of many names.

It's most likely a vector.

> With namelist <- unique(data$names) I get all the existing names.  
> But the result is a factor, not a list of strings.

as.character(data$names)  # would be a character vector, i.e., a  
structure composed of "strings"
# You could make it a list if you wanted, but it's not clear that is  
needed for your purposes.

>
> I would then like to go trough all the names in a for-loop and count  
> their occurrence.

That shows your C programming background. Try instead the loop-less  
method:

table(data$names)

BTW using "names" for an object's name is not a good programing  
practice in R because there is a useful function by the same  
name.  ..... and then there is always the "dog" fortune.
-- 
David.
>
-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT