On Sep 6, 2008, at 4:24 PM, drflxms wrote:
Hello Mr. Burns, Hello Mr. Dwinseminus
snip
David, the "input" data.frame is the result of the reshape-command I
performed. I just copied it from the R-console into the e-mail. In
fact
the first column "video" is not part of the data, but needed for
analysis with kappam.fleiss function of the irr-package. Sorry, you
are
absolutely correct, I should have mentioned this in my question. I
will
improve when I ask my next question :-).
I have not yet picked up facility with reshape. Is there a method
using reshape to take its screen output and return a dataframe?
--
David Winsemius, MD
Again I like to thank you for your help and wish you a pleasant
Sunday.
Greetings from Munich,
Felix
Patrick Burns wrote:
If I understand properly, you want
input[, -c(1, ncol(input))]
rather than
input[[, -c(video, 21)]]
Chapter 1 of S Poetry might be of interest to you.
Patrick Burns
[EMAIL PROTECTED]
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")
drflxms wrote:
Dear R-colleagues,
another question from a newbie: I am creating a lot of simple
pivot-charts from my raw data using the reshape-package. In these
charts
we have medical doctors judging videos in the columns and the videos
they judge in the rows. Simple example of chart/data.frame "input"
with
two categories 1/0:
video 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
3 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
5 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0
6 6 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0
7 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
8 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0
9 9 0 0 0 0 0 0 0 0 0 1 0 1 1 0 1 1 0 0 0 1 0
10 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
I recently learned, that I can easily create a confusion matrix
out of
this data using the following commands:
pairs<-
data.frame(pred=factor(unlist(input[2:21])),ref=factor(input[,22]))
pred<-pairs$pred
ref <- pairs$ref
library (caret)
confusionMatrix(pred, ref, positive=1)
- where column 21 is the reference/goldstandard.
My problem is now, that I analyse data.frames with an unknown
count of
columns. So to get rid of the first and last column for the "pred"
variable and to select the last column for the "ref" variable, I
have to
look at the data.frame before doing the above commands to set the
proper
column numbers.
It would be very comfortable, if I could address the last column
not by
number (where I have to count beforehand) but by a variable "last
column".
Probably there is a more easy solution for this problem using the
names
of the columns as well: the reference is always number "21" the
first
column is always called "video". So I tried:
attach(input)
pairs<-data.frame(pred=factor(unlist(input[[,-c(video,
21)]])),ref=factor(input[[21]]))
which does not work unfortunately :-(.
I'd be very happy in case someone could help me out, cause I am
really
tired of counting - there are a lot of tables to analyse...
Cheers and greetings from Munich,
Felix
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