R help - Aug 2011 - create a list under constraints

Hi, R users,

Here is an example.

k <- c(1,2,3,4,5)
i <- c(0,1,3,2,1)

if k=1, then i=0
if k=2, then i=0, 1
if k=3, then i=0, 1, 2, 3
if k=4, then i=0, 1, 2
if k=5, then i=0, 1

so i'd like to create a list like below.
> list
   k i
1  1 0
2  2 0
3  2 1
4  3 0
5  3 1
6  3 2
7  3 3
8  4 0
9  4 1
10 4 2
11 5 0
12 5 1

I tried expand.grid, but I can't.

Any suggestion will be greatly appreciated.

Regards,

Kathryn Lord 

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Hi:

Here's one way; using the mdply() function in the plyr package:

k <- c(1,2,3,4,5)
i <- c(0,1,3,2,1)

# Takes two scalars k and i as input, outputs a data frame
ff <- function(k, i) data.frame(k = rep(k, i+1), i = seq(0, i, by = 1))

library('plyr')
mdply(data.frame(k, i), ff)   # returns a data frame

# -------------
Another way to do this is to use the mapply() function
This one returns a matrix.
# -------------

gg <- function(k, i) cbind(k = rep(k, i+1), i = seq(0, i, by = 1))
do.call(rbind, mapply(gg, k, i))

HTH,
Dennis

On Tue, Aug 2, 2011 at 6:40 PM, Kathie <kathryn.lord2000 at gmail.com>
wrote:
> Hi, R users,
>
> Here is an example.
>
> k <- c(1,2,3,4,5)
> i <- c(0,1,3,2,1)
>
> if k=1, then i=0
> if k=2, then i=0, 1
> if k=3, then i=0, 1, 2, 3
> if k=4, then i=0, 1, 2
> if k=5, then i=0, 1
>
> so i'd like to create a list like below.
>
>> list
> ? k i
> 1 ?1 0
> 2 ?2 0
> 3 ?2 1
> 4 ?3 0
> 5 ?3 1
> 6 ?3 2
> 7 ?3 3
> 8 ?4 0
> 9 ?4 1
> 10 4 2
> 11 5 0
> 12 5 1
>
> I tried expand.grid, but I can't.
>
> Any suggestion will be greatly appreciated.
>
> Regards,
>
> Kathryn Lord
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/create-a-list-under-constraints-tp3714191p3714191.html
> Sent from the R help mailing list archive at Nabble.com.
>
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