From: Bob Green <bgreen_at_dyson.brisnet.org.au>

Date: Tue 02 May 2006 - 22:41:42 EST

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue May 02 22:51:05 2006

Date: Tue 02 May 2006 - 22:41:42 EST

I want to compute a new variable (newvar) based on the values of two other variables (t1freq, t2freq).The two variables (t1freq,t2freq) are contained in a dataframe - study1dat <- read.csv("c:\\study1rb.csv",header=T) .

I gather this computation can be done using Apply and I have run the following example from the help menu

## Compute row and column sums for a matrix:

x <- cbind(x1 = 3, x2 = c(4:1, 2:5)) dimnames(x)[[1]] <- letters[1:8] apply(x, 2, mean, trim = .2) col.sums <- apply(x, 2, sum) row.sums <- apply(x, 1, sum) rbind(cbind(x, Rtot = row.sums), Ctot = c(col.sums, sum(col.sums)))

My questions are:

- I don't understand what values I would need to enter for my 2 variables (data is included at end of this message) in the 'cbind' command
- For the second row, what modification is required?
- If I wanted to compute a mean, I believe the 'mean' is substituted for sum - if so, in the case where there is only one value, is it possible to obtain this as the mean rather than obtaining an NA?
- How do I save 'newvar' into the original datafile?

Any assistance with this enquiry is appreciated,

Bob

id t1freq t2freq

1 4 6 2 3 3 3 7 5 4 0 2 5 1 4 6 7 7 7 7 7 8 7 4 9 7 7 10 5 4 11 3 6 12 1 3 13 7 7 14 7 7 15 1 3 16 7 7 17 2 1 18 7 7 19 7 6 20 3 4 21 7 7 22 7 6 23 3 0 24 7 6 25 7 6 26 5 6 27 7 7 28 7 7 29 5 7 30 7 2 31 5 6 32 5 7 33 7 7 34 7 7 35 7 7 36 7 7 37 6 5 38 4 4 39 4 6 40 7 7 41 3 3 42 4 4 43 7 7 44 7 7 45 7 1 46 2 2 47 4 2 48 1 1 49 4 4 50 0 0 51 7 7 52 7 2 53 4 7 54 0 NA 55 5 4 56 0 0 57 5 5 58 5 6 59 7 7 60 5 4 61 1 4 62 6 7 63 4 5 64 6 7 65 5 4 66 1 0 67 7 7 68 5 3 69 7 7 70 4 7 71 3 7 72 7 7 73 4 2 74 4 6 75 7 5 76 0 0 77 7 6 78 3 3 79 7 7 80 2 4 81 4 1 82 1 4 83 4 2 84 2 1 85 5 0 86 1 3 87 0 0 88 7 7 89 3 1 90 6 6 91 2 1 92 4 3 ______________________________________________R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue May 02 22:51:05 2006

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