[R] R- transform data frame into matrix

From: Thorsten Raff <t.raff_at_med2.uni-kiel.de>
Date: Wed, 12 Nov 2008 17:31:44 +0100


Hello

I have the problem that I want to transform a dataframe as generated by

diagnosis <- rep(diagnosis[1:3], 3)
marker <- gl(3,3)
values <- rnorm(9)
dataframe <- cbind(diagnosis, marker, values) dataframe <- dataframe[c(1:5, 7:9), ]

into a matrix where levels(diagnosis) is indicating the rows of the matrix, levels(marker) the columns and values are the actual content of the matrix. However, as can been seen in the dataframe, some observations are missing and should result in <NAs> in the resulting matrix, giving a result like this:

marker              1         2         3
diagnosis1      value   value   value
diagnosis2      value   value   value
diagnosis3      value      NA    value

Can anyone help out with some code for this? I have tried to look this up in the mailing list as it has probably been answered before but only found aspects of the problem which I was just not able to plumb together.

Many thanks in advance, I hope this is not to much of an insult for the list.

Thorsten

P.S: I have already sent this message to the mailing list, howver I got a bounce-message back, so hopefully this is no duplicate entry. Sorry for any inconvenience that this may confer.

-- 
Thorsten Raff
2nd Medical Department,
University Hospital Schleswig-Holstein, Campus Kiel
Chemnitzstra▀e 33
24116 Kiel
GERMANY

phone: +49 431 1697-5234
fax:   +49 431 1697-1264

email: t.raff<at>med2.uni-kiel.de
web:   www.uk-s-h.de




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