[R] operations on a list

szhan@uoguelph.ca szhan at uoguelph.ca
Fri Dec 9 19:30:15 CET 2005

```Hello, Jacques,
Thank you very much for your help!
It's clever code and works fine. But I don't understand what the last line code
is for. Should I really need the last line?
Thanks again.
Josh

Quoting Jacques VESLOT <jacques.veslot at cirad.fr>:

> you could try :
>
> trt1 <- do.call("rbind", lapply(listexp, function(x) {
>     zz <- aggregate(t(x), list(rep(1:3, each=2)), mean)[,-1]
>     zz <- as.matrix(zz)
>     sweep(zz[1:2,], 2, zz[3,], "-")[1,]}))
>
> trt2 <- do.call("rbind", lapply(listexp, function(x) {
>     zz <- aggregate(t(x), list(rep(1:3, each=2)), mean)[,-1]
>     zz <- as.matrix(zz)
>     sweep(zz[1:2,], 2, zz[3,], "-")[2,]}))
>
> expeffect <- list(trt1=trt1, trt2=trt2)
>
> expeffect <- lapply(expeffect, function(x) {names(x) <- names(listexp) ; x})
>
>
>
>
> szhan at uoguelph.ca a écrit :
>
> >Hello, Everyone,
> >I am sorry that my message got truncated due to wrong format.
> >I hope it works now:
> >
> >Hello, R Users,
> >I have a list (say listexp) of 10,000 elements, each of which consists of a
> >matrix (5X6). It likes:
> >\$"a"
> >    trt1rep1    trt1rep2    trt2rep1    trt2rep2    ctlrep1    ctlrep2
> >[1,]   50        54         98         89            40         45
> >[2,]   60        65         76         79            34         43
> >[3,]   86        83         34         45            38         34
> >[4,]   67        78         88         98            45         41
> >[5,]   55        59         77         88            56         66
> >\$"b"
> >   trt1rep1    trt1rep2    trt2rep1    trt2rep2    ctlrep1    ctlrep2
> >[1,]   55        54         88         86            42         40
> >[2,]   66        65         86         99            44         48
> >[3,]   80        86         44         55            38         44
> >[4,]   77        78         98         92            35         41
> >[5,]   50        53         87         88            46         56
> >
> >.
> >
> >I want to perform some operations on the list and then got a new list(say
> >expeffect) like this:
> >1. first average two replicates for each row in the matrix shown above (like
> for
> >treatment 1 using (trt1rep1+trt1rep2)/2) and get one value for each
> >treatment/control
> >2. then subtract average value of the control from the each treatment and
> get
> >one value for the treatment effect for each row in the matrix shown above
> >3. make a new list (say trteffect) with 2 elements (trt1 and trt2), each of
> >which consists of a matrix (10,000X5)with a row name same with old list's
> >element name, a column name corresponding to the row name of old list's
> matrix
> >like:
> >\$"trt1"
> >     [,1]    [,2]    [,3]    [,4]     [,5]
> >a    9.5     24       48.5    29.5     -4
> >b   13.5     19.5     42      39.5      0.5
> >.
> >
> >\$"trt2"
> >     [,1]    [,2]    [,3]    [,4]     [,5]
> >a    51      39      3.5     50       21.5
> >b    46      46.5    8.5     57       30.5
> >.
> >
> >Joshua
> >
> >______________________________________________
> >R-help at stat.math.ethz.ch mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help