[R] Splitting a dataframe by character vector

[Ben Neal]

Thank you Jorge. 

I did get subset to work on a character vector last night, the only difference being I used two equals signs: 

(not working) > Site1 <- subset(Cover, Site = "PtaCaracol")
(working) > Site1 <- subset(Cover, Site = = "PtaCaracol")

I am unsure why this is, but it worked. I believe this was the error, causing my returned dataframes to contain all the original entries. 

Thanks again; I will explore the plyr package as well. Ben 


-----Original Message-----
From: Jorge I Velez [mailto:jorgeivanvelez at gmail.com]
Sent: Fri 4/20/2012 8:17 PM
To: Ben Neal
Subject: Re: [R] Splitting a dataframe by character vector
 
Dear Ben,

Check ?tapply, ?aggregate, ?ave for some ways to accomplish this using the
base package.  Also, check and check the plyr package at
http://plyr.had.co.nz/ along with the examples and accompanying paper.

HTH,
Jorge.-


On Fri, Apr 20, 2012 at 9:52 PM, 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).
>
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