[R] bind mean to a df

[baptiste auguie]

Hi,

You could try,

library(plyr)

ddply(data, .(name), transform, mean=mean(sale))
ddply(data, .(name), summarize, mean=mean(sale))

HTH,

baptiste

On 12 April 2011 15:46, Geoffrey Smith <gps at asu.edu> wrote:
> Hello, I would like to take the mean of a column from a data frame and then
> bind the mean back to the data frame.  I can do this using the following
> lines of code, but I am looking for a more elegant solution.  Thank you very
> much.  Geoff
>
> name <- c('Frank','Frank','Frank','Tony','Tony','Tony','Ed','Ed','Ed');
> year <- c(2004,2005,2006,2004,2005,2006,2004,2005,2006);
> sale <- c(56,45,55,65,68,70,45,67,23);
>
> data <- data.frame(name=name, year=year, sale=sale);
> data;
>
> #is there a more elegant way to add a column of means for sale by name than
> what I did below?;
>
> mean <- data.frame(aggregate(data$sale, list(data$name), mean));
> colnames(mean) <- c('name','mean');
> mean;
>
> data <- merge(data, mean);
> data;
>
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