R help - Mar 2008 - FOR LOOP w/IFELSE statement help

Dear list,
I'm trying to query a string of numbers to identify where in the string the
numbers stop increasing (where x[i] == x[i+1]). In example 1 below, I've
adapted code from Jim Holt to do this. However, I run into situations where the
condition is not met, as in example 2, where the number string is continuous. In
this case, I need to specify an alternative outcome, where if in the loop this
condition isn't met, I default to the max. of the number string
which.max(x).
 
Can someone tell me how to add an additional statement to example 2, specifying
that if in the loop, the
condition isn't found, then to give the max of the string?
 
Thanks in advance for any replies
 
### Example 1 ################### start with test string xx <-
c(3,4,5,5,6,7,8,9) result <- NULLx1 <- which.min(x)for(i in
x1:(length(x)-1)) {if((x[i] == x[i+1])) result <- c(result, x[i]) # start
with min, result = where in string x[i]==x[i+1]}                   ###Example 2
####################################x <- c(3,4,5,6,7,8,9,10) result <-
NULLx1 <- which.min(x)for(i in x1:(length(x)-1)) {if((x[i] == x[i+1])) result
<- c(result, x[i]) # condition not met; result = NULL}
 
 
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On 05-Mar-08 23:37:42, zack holden wrote:
> Dear list,
> I'm trying to query a string of numbers to identify where in the string
> the numbers stop increasing (where x[i] == x[i+1]). In example 1 below,
> I've adapted code from Jim Holt to do this. However, I run into
> situations where the condition is not met, as in example 2, where the
> number string is continuous. In this case, I need to specify an
> alternative outcome, where if in the loop this condition isn't met, I
> default to the max. of the number string which.max(x). 
>  
> Can someone tell me how to add an additional statement to example 2,
> specifying that if in the loop, the 
> condition isn't found, then to give the max of the string?
>  
> Thanks in advance for any replies
>  
>### Example 1 ################### start with test string
> xx <- c(3,4,5,5,6,7,8,9)
> result <- NULLx1 <- which.min(x)
> for(i in x1:(length(x)-1)){
>  if((x[i] == x[i+1])) result <- c(result,x[i])
># start with min, result = where in string x[i]==x[i+1]}                
> 
>###Example 2 ####################################
> x <- c(3,4,5,6,7,8,9,10)
> result <- NULLx1 <- which.min(x)
> for(i in x1:(length(x)-1)){
>  if((x[i] == x[i+1])) result <- c(result, x[i])
># condition not met; result = NULL} 
I would rather do this in the following kind of way:
### Example 1:
xx <- c(3,4,5,5,6,7,8,9)
nn <- length(xx)
if(any(xx[1:(nn-1)]==xx[2:nn])){
  min(which(xx[1:(nn-1)]==xx[2:nn]))
  } else max(xx)
### Result: [1] 3

### Example 2:
x <- c(3,4,5,6,7,8,9,10)
n <- length(x)
if(any(x[1:(n-1)]==x[2:n])){
  min(which(x[1:(n-1)]==x[2:n]))
  } else max(x)
### Result: [1] 10

Best wishes,
Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 05-Mar-08                                       Time: 23:45:05
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