[R] Splitting a dataframe by character vector

[Rolf Turner]

On 21/04/12 13:52, Ben Neal wrote:
> I am just trying to split a dataframe of 750 observations of 29 variables by "Site", which is a vector in the dataframe with five text names (ex. PtaCaracol). I just want to generate summary statistics for my other variables for each site individually.
>
> I know this should be simple, and I did read up on options, choosing to use "subset", but I am honestly confounded that this does not result in a new dataframe split by this factor. I tried "subset" with an argument based on my various other numeric vectors, and it worked just fine. My very simple code is below, and thank you for any responses. I apologize for asking such a simple question, but I wrote this out exactly as found it in an exactly similar question, which indicated this should work. Now I am confused! Thank you for any assistance. Ben Neal
>
> # Load data from CSV file
> Cover = read.csv ("/Users/benjaminneal/Documents/1110_Panama/Transect series /1210_BocasTransectSummary.csv",
>                             header=T)
> # Divide dataframe by Site names
> Site1<- subset(Cover, Site = "PtaCaracol")
>
> PS The csv loads fine, gives normal summary stats, and does not seem to be the issue. I thought about just renaming by hand all the sites in the file (i.e. "PtaCaracol"=1 . . but this seems like a weak solution).

What about a ***reproducible*** example?

What isn't working?  What (if any) error message did you get?

I am at least 99% confident that numeric versus character values in 
Cover$Site
is completely irrelevant.

My ***guess*** (and it can only be a guess, given the vagueness and
lack of detail in your question) is that you need a double ("logical")
equals sign.  I.e. I suspect that

Site1<- subset(Cover, Site == "PtaCaracol")

will work.

That being said --- since you want to *split* your  data frame by "Site" ---
why the <expletive deleted> don't you use split()???

E.g.:

     Splitz <- split(Cover,Cover$Site)

     cheers,

         Rolf Turner