# [R] For loop with i and j and multiple if statements... help!

Pieter Schoonees schoonees at ese.eur.nl
Thu Oct 18 14:20:32 CEST 2012

```Without commenting on the method itself, shouldn't you be using both x and y twice within each loop instead of x three times and y only once?

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of ingaschwabe
> Sent: Thursday 18 October 2012 12:36
> To: r-help at r-project.org
> Subject: [R] For loop with i and j and multiple if statements... help!
>
> Dear all!
>
> I'm quite new to R and at this moment a little bit lost in trying to
> make a function work with a for loop that has two variables (i and j)
> and multiple if statements..
> I hope that someone of you could help me. I would very appreciate it!
>
> What do I want to do? I am analysing the data of an 'eye tracker'. The
> eye tracker registers the coordinates to which participants looked
>
> The data looks like this:
>
>  Number   x   y
> 1      1 701 209
> 2      2 685 209
> 3      3 566 248
> 4      4 562 234
> 5      5 601 225
> 6      6 608 232
> [....]
>
> To assign look zones, I looked which zone (e.g. the references) is
> represented by which coordinates. This give the following results:
> Look zone 1 = x > 170, x < 1250, y > 150 and y < 480 look sone 2 = x >
> 170, x < 420, y > 480 and y < 810.
>
> Now I would like to assign a lookzone for each subject by the means of
> a function with a for loop.
>
>
> lookzones <- function(input){
>
>                 lookzone <- matrix(0, nrow(input), 1)#Make space for
> lookzone variables
>
> for(i in 1:nrow(input)){
> for(j in 1:nrow(input)){
>                  if (x[i] > 170 && x[i] < 1250 && x[j] > 150 && y[j] <
> 480) {lookzone <- 1}
>                  if (x[i] > 170 && x[i] < 420  && x[j] > 480 && y[j] <
> 810) {lookzone <- 2}
>                           }
>             list(lookzone = lookzone)
>                     input <- cbind(input, lookzone)
>                         }
> }
>
> First, there is a variable made (lookzone) in which the values of the
> lookzones can be stored. Then in the for loop, it is tested whether all
> conditions are met (see above) and then a value is assigned to the
> lookzone variable.
> The input variable is a data set that looks like the data above.
>
> However, the function does not seem to work.
> When I run it, R assigns a value '1' to every x/y combination.
>
> Can someone help me with this?
>
> Thank you so much !
>
> Bye, inga
>
>
>
> --
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> with-i-and-j-and-multiple-if-statements-help-tp4646596.html
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