R help - Jul 2012 - Finding and manipulation clusters of numbers in a sequence of numbers

Hi,

I have the following sequence:
in <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
>From this sequence I would like to get to the following sequence:
out <- c(0, 0, 0, 3, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0,
0, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 2, 0, 2, 0, 0, 2)

Basically, what I would like to do for each number greater than 0,  is to
add all adjacent numbers and the adjacent numbers of those numbers, etc.
until one of those numbers is equal to 0.

I could manually repeat the loops below until "sequence" stops
changing but
there must be a smarter way. Any suggestions? Thanks!

sequence <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0,
0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
    for (h in 2:(length(sequence) - 1))
      {
      sequence[h] <- ifelse(sequence[h] > 0, sequence[h-1] + sequence[h],
0)
      }
    
    for (h in 1:(length(sequence) - 1))
      {
      sequence[h] <- ifelse(sequence[h] > 0 & sequence[h+1] >
sequence[h],
sequence[h+1], sequence[h])
      }  

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On Mon, Jul 16, 2012 at 12:17 PM, mdvaan <mathijsdevaan at gmail.com>
wrote:
> Hi,
>
> I have the following sequence:
> in <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0,
0, 0,
> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
>
> >From this sequence I would like to get to the following sequence:
> out <- c(0, 0, 0, 3, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0,
0,
> 0, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 2, 0, 2, 0, 0, 2)
>
> Basically, what I would like to do for each number greater than 0,  is to
> add all adjacent numbers and the adjacent numbers of those numbers, etc.
> until one of those numbers is equal to 0.
>
Here cumsum(input == 0) * (input !=0) replaces each run of non-zeros
with a distinct group number and then ave is used to sum over the
distinct groups:
> ave(input, cumsum(input == 0) * (input != 0), FUN = sum)
 [1]  0  0  0  3  3  0  0  0  1  0  0  0  0  0  0  0  1  0  1  0  0  0
 0 11 11 11 11 11 11 11 11 11 11 11  0  2  0  2  0  0  2



-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

Is f() what you want?  It wastes some time doing things that don't
have to be done but is pretty easy to understand.
  > input <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0,
0, 0, 0,
  + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
  > out <- c(0, 0, 0, 3, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0,
0, 0,
  + 0, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 2, 0, 2, 0, 0, 2)
  > f <- function (x)  {
      firstInRun <- function(x) c(TRUE, x[-1] != x[-length(x)])
      group <- cumsum(firstInRun(x == 0))
      ave(x, group, FUN = sum)
  }
  > all.equal(out, f(input))
  [1] TRUE

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On
> Behalf Of mdvaan
> Sent: Monday, July 16, 2012 9:18 AM
> To: r-help at r-project.org
> Subject: [R] Finding and manipulation clusters of numbers in a sequence of
numbers
> 
> Hi,
> 
> I have the following sequence:
> in <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0,
0, 0,
> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
> 
> >From this sequence I would like to get to the following sequence:
> out <- c(0, 0, 0, 3, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0,
0,
> 0, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 2, 0, 2, 0, 0, 2)
> 
> Basically, what I would like to do for each number greater than 0,  is to
> add all adjacent numbers and the adjacent numbers of those numbers, etc.
> until one of those numbers is equal to 0.
> 
> I could manually repeat the loops below until "sequence" stops
changing but
> there must be a smarter way. Any suggestions? Thanks!
> 
> sequence <- c(0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1,
0, 0,
> 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 0, 2)
>     for (h in 2:(length(sequence) - 1))
>       {
>       sequence[h] <- ifelse(sequence[h] > 0, sequence[h-1] +
sequence[h], 0)
>       }
> 
>     for (h in 1:(length(sequence) - 1))
>       {
>       sequence[h] <- ifelse(sequence[h] > 0 & sequence[h+1] >
sequence[h],
> sequence[h+1], sequence[h])
>       }
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/Finding-and-
> manipulation-clusters-of-numbers-in-a-sequence-of-numbers-tp4636661.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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