R help - Jan 2006 - Why doesn't this nested loop work?

Hi there,

 

I can get the for-loop to work, I can get the while loop to work.  But I
can't get a for loop to work nested within the while loop - why?  

 

Please help,

Teresa

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"Teresa Nelson" <jtanelson at centurytel.net> writes:
> Hi there,
> 
>  
> 
> I can get the for-loop to work, I can get the while loop to work.  But I
> can't get a for loop to work nested within the while loop - why?  
> 
What do you mean it doesn't work??

I get:
>
> results
       [,1] [,2]
  [1,]    1   25
  [2,]    2   50
  [3,]    3   75
  [4,]    4  100
  [5,]    5  125
  [6,]    6  150
  [7,]    7  175
  [8,]    8  200
  [9,]    9  225
 [10,]   10  250
 [11,]   11  275
 [12,]   12  300
 [13,]    0    0
...
[107,]    0    0
[108,]  108  300
[109,]    0    0
[110,]  110  275
[111,]    0    0
[112,]    0    0
[113,]    0    0
[114,]    0    0
[115,]    0    0
[116,]    0    0
[117,]    0    0
[118,]    0    0
[119,]    0    0
[120,]  120  300

If that's not what you expected, then you need to adjust your
expectations. Notice that your k's are effectively
> outer(1:12,1:10)
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1    2    3    4    5    6    7    8    9    10
 [2,]    2    4    6    8   10   12   14   16   18    20
 [3,]    3    6    9   12   15   18   21   24   27    30
 [4,]    4    8   12   16   20   24   28   32   36    40
 [5,]    5   10   15   20   25   30   35   40   45    50
 [6,]    6   12   18   24   30   36   42   48   54    60
 [7,]    7   14   21   28   35   42   49   56   63    70
 [8,]    8   16   24   32   40   48   56   64   72    80
 [9,]    9   18   27   36   45   54   63   72   81    90
[10,]   10   20   30   40   50   60   70   80   90   100
[11,]   11   22   33   44   55   66   77   88   99   110
[12,]   12   24   36   48   60   72   84   96  108   120

and that in that table some numbers occur up to five times and others
not at all.

  
> 
> Please help,
> 
> Teresa
> 
> 
> #  Why doesn't this nested loop work?
> 
> n.max <- 300
> NUM <- 25
> 
> n.sim <- 10 
> j <- (n.max/NUM)*n.sim
> 
> results <- matrix(0, nrow=j, ncol=2)
> 
> while(NUM <= n.max){
> 
> for(i in 1:n.sim){
> 
> k <- (NUM/25)*i
> 
> results[k,1] <- k
> results[k,2] <- NUM
> 
> } 
> 
> NUM <- NUM + 25
> 
> }
> 
> results
> 
> #### TRY WHILE LOOP ONLY
> 
> results <- matrix(0, nrow=12, ncol=2)
> 
> n.max <- 300 
> NUM <- 25
> 
> while(NUM <= n.max){ 
> 
> k <- NUM/25
> 
> results[k,1] <- k 
> results[k,2] <- NUM 
> 
> NUM <- NUM + 25
> 
> }
> 
> results
> 
> # It works, here are the results
> 
> #      [,1] [,2]
> # [1,]    1   25
> # [2,]    2   50
> # [3,]    3   75
> # [4,]    4  100
> # [5,]    5  125
> # [6,]    6  150
> # [7,]    7  175
> # [8,]    8  200
> # [9,]    9  225
> #[10,]   10  250
> #[11,]   11  275
> #[12,]   12  300
> 
> 
> 
> ### Try For Loop Only 
> 
> n.sim <- 10
> NUM <- 25
> 
> results <- matrix(0, nrow=10, ncol=2)
> 
> for(i in 1:n.sim){
> 
> results[i,1] <- i
> results[i,2] <- NUM
> 
> } 
> 
> results
> 
> # it works, here are the results 
> #      [,1] [,2]
> # [1,]    1   25
> # [2,]    2   25
> # [3,]    3   25
> # [4,]    4   25
> # [5,]    5   25
> # [6,]    6   25
> # [7,]    7   25
> # [8,]    8   25
> # [9,]    9   25
> #[10,]   10   25
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Teresa Nelson
> Hi there,
> 
> 
> 
> I can get the for-loop to work, I can get the while loop to work.  But
I
> can't get a for loop to work nested within the while loop - why?
> 
> 
> 
> Please help,
> 
> Teresa
It actually does work, but I think the problem is with your matrix
indexing.  See the sample below.  

You could also check out ?seq, ?rep, and ?apply for solving this problem
with fewer lines of code.


 n.max <- 300
 NUM <- 25
 
 n.sim <- 10 
 j <- (n.max/NUM)*n.sim
 
 results <- matrix(0, nrow=j, ncol=2)
 
 while(NUM <= n.max){
 
 for(i in 1:n.sim){
 
 k <- (NUM/25)*i
 
 results[((NUM / 25) - 1) * n.sim + i, 1] <- k
 results[((NUM / 25) - 1) * n.sim + i, 2] <- NUM
 cat("Iteration", i, ": NUM=", NUM, "k=", k,
"\n")
 
 } 
 
 NUM <- NUM + 25
 }
This email message, including any attachments, is for the so...{{dropped}}

Is this what you are searching for?

n.max <- 300
NUM <- 25
id<-0

n.sim <- 10 
j <- (n.max/NUM)*n.sim

results <- matrix(0, nrow=j, ncol=2)

while(NUM <= n.max){

for(i in 1:n.sim){

k <- (NUM/25)*i
id<-id+1
results[id,1] <- k
results[id,2] <- NUM

} 

NUM <- NUM + 25

}

results
<<<


If not, plase give an example how you would like the results to look like!

Best,
Ales Ziberna

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Teresa Nelson
Sent: Wednesday, January 04, 2006 4:44 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Why doesn't this nested loop work?

Hi there,

 

I can get the for-loop to work, I can get the while loop to work.  But I
can't get a for loop to work nested within the while loop - why?  

 

Please help,

Teresa