bind mean to a df

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Hi Geoffrey,

Here is one option (data named dfrm instead of data because data() is
a function too):

## Data
dfrm <- data.frame(
  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))
## Using with() to avoid typing names and ave() to do the work
dfrm$mean <- with(dfrm, ave(x = sale, name, FUN = mean))
## look at the results
dfrm

Cheers,

Josh
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;

? ? ? ?[[alternative HTML version deleted]]

______________________________________________
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Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/
Hi,

You could try,

library(plyr)

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

HTH,

baptiste
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;

? ? ? ?[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.