Replace the y[1] with x[2] in the apply function - there is no 'y' defined in the function passed to apply. In the apply function, x is an 2-element vector representing a single row of the data (since the 1 in the second argument of apply says that it is applied row-wise). So the second element, i.e. x[2], is actually the y value. The name 'x' in function has nothing to do with the column 'x' in the data - it is the name of the argument sent to the function.
Also, Sarah's code is vectorized (thus more elegant and efficient etc, and does not use a loop) so I suggest you stick with that. > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of ingaschwabe > Sent: Thursday 18 October 2012 4:51 > To: r-help@r-project.org > Subject: Re: [R] For loop with i and j and multiple if statements... > help! > > Dear all, > > Thanks for the many replies! > > Indeed, the function does not represent my explanation. It should have > been: > > if (x[i] > 170 && x[i] < 1250 && y[j] > 150 && y[j] < 480) > > Sorry, my mistake. > > My data looks like this: > head(input[,3:4]) > x y > 1 701 209 > 2 685 209 > 3 566 248 > 4 562 234 > 5 601 225 > 6 608 232 > > > Refering to the last post, I guess that my function then should look > like something like this: > > test <- apply(input,1,function(x){ > lookzone<-NULL > if (x[1] > 170 && x[1] < 1250 && y[1] > 150 && y[1] < > 480) > {lookzone<-1} > if (x[1] > 170 && x[1] < 420 && y[1] > 480 && y[1] < > 810) > {lookzone <- 2} > return(lookzone) > }) > > however, when I run the function then nothing happens. > > and when I ask explicitly for the result then I get this > > test > NULL > > Can someone tell me what goes wrong here? Or give a hint? > I'm not used to using the apply function and do use the for loop on the > basis of an example that I once made so I am not a very experienced R > user.. > > Thank you so much for your help! > I really appreciate it! > > Bye,inga > > > > -- > View this message in context: http://r.789695.n4.nabble.com/For-loop- > with-i-and-j-and-multiple-if-statements-help-tp4646596p4646630.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
