[R] How to calculate the mean of all values in a list or dataframe

[Bert Gunter]

?unlist
mean(unlist(test)) 


Bert Gunter
Genentch Nonclinical Statistics


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of B. Bogart
Sent: Friday, January 11, 2008 11:29 AM
To: r-help at r-project.org
Subject: [R] How to calculate the mean of all values in a list or dataframe

Hello all,

I've scoured the archives and google and I can't figure out how to
amalgamate a set of vectors of differing lengths in such a way as I can
calculate the mean easily.

The following dummy example contains vectors of length 1, but my data
has vectors of various lengths.

R> test = list(); for(i in 1:5) {test = append(test, i)}

R> test
[[1]]
[1] 1

[[2]]
[1] 2

[[3]]
[1] 3

[[4]]
[1] 4

[[5]]
[1] 5

R> mean(test)
[1] NA
Warning message:
argument is not numeric or logical: returning NA in: mean.default(test)

I need to be able to construct the structure in a loop, but it does not
really matter what type that structure is. I just want to be able to
boxplot() and mean() and other simple functions. Each index in the list
(as in the case above) can be considered a run of a test, the values in
that index the results of that run, which have different number of
elements. I would like the mean of all the values in all the runs.

What is the best type for collecting a set of numeric vectors of
differing lengths in a for loop for the most flexibility and ease of
using functions on the whole data or parts of it?

Thanks for your time,
B. Bogart

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