Combine data frame by individuals and find means

Question

I'm new to r so I'm not sure if I'll ask my own question right but I have a data frame from a study and it provided a data set:

that I trimmed down to what I needed to combine in the picture, I've been trying to find a way to combine each individual(e) and take the mean of each observation(w) so that I'll end up with one row for each individual and the mean of its combined observations. I know how to do this if I do it all separately with

mean(m$`30901`$deltaon)

(m is the original list) but I wanted to find a way so that it goes

mean(m$indivduals[1:40]$deltaon)

so that it will give the means for each. I've been trying to mess with for loops but I cant seem to figure it out.

Are we talking [mean by group](http://stackoverflow.com/questions/21982987/mean-per-group-in-a-data-frame)? — David Arenburg, Apr 09 '16 at 20:03

score 1 · Answer 1 · edited Apr 09 '16 at 19:37

1

we can use data.table for this problem:

         install.packages("data.table")
         library(data.table)
         m<-data.table(e,w)
         mean(m$individual[1:40]*m$deltaon)

think this will help you.

edited Apr 09 '16 at 19:37

RHA

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answered Apr 09 '16 at 16:21

Sorif Hossain

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How are you using data table here? Once you use `$` it no longer matters that `m` was a data table. – Rich Scriven Apr 09 '16 at 19:56

Combine data frame by individuals and find means

1 Answers1