[R] help with vector operation
Uwe Ligges
ligges at statistik.uni-dortmund.de
Mon Jan 31 18:46:11 CET 2005
eesteves at ualg.pt wrote:
> Dear All,
>
> I'm trying to calculate the following:
Select the rows of the data.frame and just calculate what you already
have written:
> g.rate<-(SL-int)/NO
For the lines you cited this means, e.g.:
X <- data.frame(CODE = c(123:125, 234),
SL = c(12.5, 11.4, 10.8, 16.9),
NO = c(14, 13, 11, 19),
DAY = c(88, 88, 101, 172))
int <- c(9.32, 8.43, NA, 9.81)
g.rate <- with(X, (SL - int) / NO)
That's it!
Uwe Ligges
> where SL and NO are individual length and counts for the same subject, and the
> int value is a day-specific value i.e. for each DAY=88, 101..., 172 I'd like to
> use a different values of int=9.32, 8.43, ..., 9.81. All variables are compiled
> in a larger data.frame of the form:
>
> CODE SL NO DAY (...)
> 123 12.5 14 88
> 124 11.4 13 88
> 125 10.8 11 101
> (...)
> 234 16.9 19 172 (...)
>
> I've been trying apply() but with little (NONE) success!
> Thanks, Eduardo Esteves
>
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