R help - Mar 2013 - how to search a list that contains multiple dissimilar vectors?

Dear All,

This is a simple question, but I'm stumped about the simplest way to search
a list object such as the following:

This randomish snippet:

n <- c(round(runif(round(runif(1,1,10),0),1,10),0))
alist <- new("list")
for (i in seq_along(n)) {
	alist[[i]] <- c(round(runif(round(runif(1,1,10),0),1,10),0))
}
names(alist) <- sample(letters[1:length(n)])
rm(n);c(alist)


...produces something like this:

$d
[1] 4

$b
[1] 3 5 3

$a
[1]  2  5  7  3 10  3  4  9  9

$c
[1]  6  3  7  4  5 10  8 10  3

My question is how does one search the list for a given value, in a most
compressed set of commands, in order two return two separate indices: a) the
index of the list element(s) containing the value, and b) the index of the
matching value(s) within the vector.

Right now, I'm writing cumbersome loops to iterate though the elements, but
there must be a simple, effective method to which I have not found a reference.

Many thanks in advance, and apologies if I have overlooked a reference passage.
Best,
Eric

--
 Eric Rupley
 University of Michigan, Museum of Anthropology
 1109 Geddes Ave, Rm. 4013
 Ann Arbor, MI 48109-1079

Hi Eric,
something like the following might me a starter

(index<-lapply(alist,function(x)which(x==x.search)))

cheers.

Am 28.03.2013 08:40, schrieb Eric Rupley:
> 
> Dear All,
> 
> This is a simple question, but I'm stumped about the simplest way to
search a list object such as the following:
> 
> This randomish snippet:
> 
> n <- c(round(runif(round(runif(1,1,10),0),1,10),0))
> alist <- new("list")
> for (i in seq_along(n)) {
> 	alist[[i]] <- c(round(runif(round(runif(1,1,10),0),1,10),0))
> }
> names(alist) <- sample(letters[1:length(n)])
> rm(n);c(alist)
> 
> 
> ...produces something like this:
> 
> $d
> [1] 4
> 
> $b
> [1] 3 5 3
> 
> $a
> [1]  2  5  7  3 10  3  4  9  9
> 
> $c
> [1]  6  3  7  4  5 10  8 10  3
> 
> My question is how does one search the list for a given value, in a most
compressed set of commands, in order two return two separate indices: a) the
index of the list element(s) containing the value, and b) the index of the
matching value(s) within the vector.
> 
> Right now, I'm writing cumbersome loops to iterate though the elements,
but there must be a simple, effective method to which I have not found a
reference.
> 
> Many thanks in advance, and apologies if I have overlooked a reference
passage.
> Best,
> Eric
> 
> --
>  Eric Rupley
>  University of Michigan, Museum of Anthropology
>  1109 Geddes Ave, Rm. 4013
>  Ann Arbor, MI 48109-1079
>  
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

-- 
Eik Vettorazzi

Department of Medical Biometry and Epidemiology
University Medical Center Hamburg-Eppendorf

Martinistr. 52
20246 Hamburg

T ++49/40/7410-58243
F ++49/40/7410-57790
--
Pflichtangaben gem?? Gesetz ?ber elektronische Handelsregister und
Genossenschaftsregister sowie das Unternehmensregister (EHUG):

Universit?tsklinikum Hamburg-Eppendorf; K?rperschaft des ?ffentlichen Rechts;
Gerichtsstand: Hamburg

Vorstandsmitglieder: Prof. Dr. Martin Zeitz (Vorsitzender), Dr. Alexander
Kirstein, Joachim Pr?l?, Prof. Dr. Dr. Uwe Koch-Gromus

Hi, Eric,

as a quick hack, does

spots <- sapply( alist,
                  function( listcomp)
                   which( listcomp == value.to.look.for) )

spots[ sapply( spots, length) == 0] <- NULL

do what you want?


Regards  --  Gerrit


On Thu, 28 Mar 2013, Eric Rupley wrote:
>
> Dear All,
>
> This is a simple question, but I'm stumped about the simplest way to 
> search a list object such as the following:
>
> This randomish snippet:
>
> n <- c(round(runif(round(runif(1,1,10),0),1,10),0))
> alist <- new("list")
> for (i in seq_along(n)) {
> 	alist[[i]] <- c(round(runif(round(runif(1,1,10),0),1,10),0))
> }
> names(alist) <- sample(letters[1:length(n)])
> rm(n);c(alist)
>
>
> ...produces something like this:
>
> $d
> [1] 4
>
> $b
> [1] 3 5 3
>
> $a
> [1]  2  5  7  3 10  3  4  9  9
>
> $c
> [1]  6  3  7  4  5 10  8 10  3
>
> My question is how does one search the list for a given value, in a most
compressed set of commands, in order two return two separate indices: a) the
index of the list element(s) containing the value, and b) the index of the
matching value(s) within the vector.
>
> Right now, I'm writing cumbersome loops to iterate though the elements,
but there must be a simple, effective method to which I have not found a
reference.
>
> Many thanks in advance, and apologies if I have overlooked a reference
passage.
> Best,
> Eric
>
> --
> Eric Rupley
> University of Michigan, Museum of Anthropology
> 1109 Geddes Ave, Rm. 4013
> Ann Arbor, MI 48109-1079
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>