Hi:
If I understood you correctly, the following may work:
# Utility function to compute all pairwise differences of a vector:
# The upper triangle subtracts x_i - x_j for j > i; if you want it the
# other way around, use lower.tri() instead of upper.tri().
# Coercion to vector means that the differences from x_1 appear
# first, followed by those from x_2, then x_3, etc.
subtfun <- function(x) {
u <- outer(x, x, '-')
as.vector(u[upper.tri(u)])
}
# To apply it to each of A, B, C in each Thesis:Day subgroup,
# here's one way with function ddply() in the plyr package:
library(plyr)
v <- ddply(df, .(Thesis, Day), numcolwise(subtfun))
head(v)
HTH,
Dennis
On Fri, Jan 14, 2011 at 1:17 AM, romzero <romz...@yahoo.it> wrote:
>
> Hi, i have that table
>
>
>
> Thesis Day A B C
> 1 0 83.43 90.15 22.97
> 1 0 85.50 94.97 16.62
> 1 0 83.36 95.38 20.70
> 1 0 84.47 92.16 23.58
> 1 0 83.98 95.33 19.39
> 1 0 82.86 93.78 24.55
> 1 0 83.39 92.67 19.56
> 1 0 85.17 95.24 17.95
> 1 0 81.62 93.32 28.49
> 1 0 82.99 92.85 19.73
> 1 0 81.11 95.67 27.20
> 1 0 83.39 94.69 16.51
> 1 0 79.56 89.87 30.39
> 1 0 80.54 93.32 21.76
> 1 0 82.11 92.58 22.17
> 1 14 85.65 94.00 19.19
> 1 14 85.06 92.44 20.44
> 1 14 83.97 91.39 24.38
> 1 14 84.61 91.97 19.44
> 1 14 85.13 90.59 25.30
> 1 14 84.81 91.01 19.80
> 1 14 84.52 94.06 18.77
> 1 14 84.30 94.49 24.90
> 1 14 84.74 91.32 20.35
> 1 14 84.08 94.12 22.96
> 1 14 84.50 94.25 19.95
> 1 14 84.02 94.74 20.35
> 1 14 85.30 92.82 21.12
> 1 14 85.08 91.14 24.16
> 1 14 85.21 95.69 18.17
> etc etc etc etc etc
> 2 0 83.43 90.15 22.97
> 2 0 85.50 94.97 16.62
> 2 0 83.36 95.38 20.70
> 2 0 84.47 92.16 23.58
> 2 0 83.98 95.33 19.39
> 2 0 82.86 93.78 24.55
> 2 0 83.39 92.67 19.56
> 2 0 85.17 95.24 17.95
> 2 0 81.62 93.32 28.49
> 2 0 82.99 92.85 19.73
> 2 0 81.11 95.67 27.20
> 2 0 83.39 94.69 16.51
> 2 0 79.56 89.87 30.39
> 2 0 80.54 93.32 21.76
> 2 0 82.11 92.58 22.17
> 2 14 84.48 91.23 20.44
> 2 14 85.22 93.08 22.54
> 2 14 83.89 92.74 25.11
> etc etc etc etc etc
>
> I need to subtract from every number the other numbers of the same thesis
> and same day.
>
> Example:
> A(row1) - A (row2) (same for B and C)
> A(row1) - A (row3)
> etc until the last Thesis 1 and Day 0
> A(row2) - A (row3)
> etc etc until the last Thesis 1 and Day 0
>
> Same for the others theses and days.
>
> How can i do that?
>
> Sorry for my english.
> --
> View this message in context:
> http://r.789695.n4.nabble.com/test-tp3217329p3217329.html
> Sent from the R help mailing list archive at Nabble.com.
>
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