[R] OK - I got the data - now what? :-)

[hadley wickham]

>   I think the root cause of a number of my coding problems in R right
> now is my lack of skills in reading and grabbing portions of the data
> out of arrays. I'm new at this. (And not a programmer) I need to find
> some good examples to read and test on that subject. If I could locate
> which column was called C1, then read row 3 from C1 up to the last
> value before a 0, I'd have proper data to plot for one line. Repeat as
> necessary through the array and I get all the lines. Doing the lines
> one at a time should allow me the opportunity to apply color or not
> plot based on values in the first few columns.
>
> Thanks,
> Mark
>
> test <- data.frame(A=1:10, B=100, C1=runif(10), C2=runif(10),
> C3=runif(10), C4=runif(10), C5=runif(10), C6=runif(10))
> test<-round(test,2)
>
> #Make array ragged
> test$C3[2]<-0;test$C4[2]<-0;test$C5[2]<-0;test$C6[2]<-0
> test$C4[3]<-0;test$C5[3]<-0;test$C6[3]<-0
> test$C6[7]<-0
> test$C4[8]<-0;test$C5[8]<-0;test$C6[8]<-0
>
> #Print array
> test

Are the zeros always going to be arranged like this? i.e. for
experiment there is a point at which all later values are zero?  If
so, the following is a much simpler way of getting to the core of your
data, without fussing with overly complicated matrix indexing:

library(reshape)
testm <- melt(test, id = c("A", "B"))
subset(testm, value > 0)

I suspect you will also find this form easier to plot and analyse.

Hadley

-- 
http://had.co.nz/