[R] averaging pairs of columns in a dataframe

[Gasper Cankar]

 somehow robust method for dataframe df would be

newdf <- (df[,seq(1,66,2)]+df[,seq(2,66,2)])/2


Gasper


-----Original Message-----
From: JonD [mailto:jonathan.denniss at googlemail.com] 
Sent: Wednesday, August 27, 2008 3:47 PM
To: r-help at r-project.org
Subject: [R] averaging pairs of columns in a dataframe


Dear all,

I have a dataframe with 132 columns and 100 rows.  Every 2nd column is a
repeat measurement so that the columns could be titled, a a b b c c d d etc.

I would like to average the repeats such that I am left with a data frame of
66 columns (of means) and 100 rows.  

I have been trying to use rowMeans but have not been able to average the
pairs of columns, only the whole dataframe.

Any help would be appreciated, I am new to R.

Thanks in advance,

Jon.
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