[R] R for loop stops after 4 iterations

[Dennis Murphy]

Hi:

Here are a couple of ways, using the data snippet you provided as the
input data frame e.

Start by defining the function, which outputs a percentage:

f <- function(n, mean, sd) {
    s <- rnorm(n, mean = mean, s = sd)
    round(100 * sum(s > 0.42)/length(s), 4)
   }


(1) Use the plyr package and its mdply() function. Note that
     the columns of epars have the same names as the arguments
     of f.

library('plyr')
mdply(epars, f)
     n mean   sd      V1
1 1673 0.36 0.08 24.0287
2  167 0.36 0.08 23.9521
3   99 0.37 0.06 18.1818
4  116 0.38 0.07 22.4138
5   95 0.41 0.08 40.0000

(2) Split the columns of e into vectors and use mapply():

ssize <- e[, 1]
mns <- e[, 2]
sds <- e[, 3]
mapply(f, ssize, mns, sds)
[1] 21.3987 19.1617 22.2222 32.7586 45.2632

mapply() just returns the percentages. The percentages are different
between the two calls because the samples are different.

HTH,
Dennis


On Sat, Oct 22, 2011 at 4:33 PM, Philip Robinson
<philip.c.robinson at gmail.com> wrote:
> I have a data frame called e, dim is 27,3, the first 5 lines look like this:
>
>
>
>
>
>     V1   V2   V3        V4
>
> 1  1673 0.36 0.08  Smith
>
> 2 167 0.36 0.08     Allen
>
> 3    99 0.37 0.06     Allen
>
> 4   116 0.38 0.07     Allen
>
> 5    95 0.41 0.08     Allen
>
>
>
> I am trying to calculate the proportion/percentage of V1 which would have
> values >0.42 if V2 was the mean of a normal distribution with V1 people and
> a standard distribution of V3. The loop works but only for 4 iterations then
> stops, I can't understand why, the code and the output are below
>
>
>
>
>
> output <- rep(NA, 27)
>
> for (i in 1:length(e))
>
> {
>
> x <- rnorm(n=e[i,1], mean=e[i,2], sd=e[i,3])
>
> n <- e[i,1]
>
> v <- x>0.42
>
> q <-(sum(v)/n)*100
>
> output[i] <- q
>
> }
>
>
>
>>output
>
> [1] 22.23551 27.54491 25.25253 19.82759       NA       NA       NA       NA
> NA
>
> [10]       NA       NA       NA       NA       NA       NA       NA       NA
> NA
>
> [19]       NA       NA       NA       NA       NA       NA       NA       NA
> NA
>
>
>        [[alternative HTML version deleted]]
>
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