Jill, Are you trying to create a subset of the data for which variable 7=0, variable 3=1, and variable 11= 0 or 1? In that case there is no need for a lop. You just do: subset <- plomin[,7]==1 & plomin[,3]==0 & (plomin[,11]==1 | plomin[,11]==0) subset will be a logical vector that has length n. it will be equal to true if all three conditions are true. Use this to subset the data. sub.plomin <- plomin[subset,] think about how this treats missing values. Jens

Jeremy, Glad this was helpful. ? basically we want to choose the data points for which plomin[,11] is NA or 0, but not 1. Is there a way of doing this via subset - or do we need to recode the data? You can simply do this using: & (is.na(plomin[,11])=T | plomin[,11])==0) Then the but not 1 part is redundant. Hth, Jens From: gov2001-l-bounces at lists.fas.harvard.edu [mailto:gov2001-l-bounces at lists.fas.harvard.edu] On Behalf Of Jeremy Hodgen Sent: Tuesday, March 25, 2008 5:42 PM To: gov2001-l at lists.fas.harvard.edu Subject: Re: [gov2001-l] SPSS data Jens Thanks for this. Clearly no need for a loop but the data does behave very oddly - I don't know why the logical expression doesn't work in the code that we had - the only reason that I can see is that plomin[,11] has missing data whereas the other two do not. However, your code does seem to work - except that in this case, we do want to keep the missing data in - so basically we want to choose the data points for which plomin[,11] is NA or 0, but not 1. Is there a way of doing this via subset - or do we need to recode the data? Jeremy On 25 Mar 2008, at 17:42, Jens Hainmueller wrote: Jill, Are you trying to create a subset of the data for which variable 7=0, variable 3=1, and variable 11= 0 or 1? In that case there is no need for a lop. You just do: subset <- plomin[,7]==1 & plomin[,3]==0 & (plomin[,11]==1 | plomin[,11]==0) subset will be a logical vector that has length n. it will be equal to true if all three conditions are true. Use this to subset the data. sub.plomin <- plomin[subset,] think about how this treats missing values. Jens -----Original Message----- From: gov2001-l-bounces at lists.fas.harvard.edu [mailto:gov2001-l- bounces at lists.fas.harvard.edu] On Behalf Of Jill Hohenstein Sent: Tuesday, March 25, 2008 1:34 PM To: gov2001-l at lists.fas.harvard.edu Subject: Re: [gov2001-l] SPSS data Thanks for your quick reply! Sorry, the line really read like this: if (plomin[i,7] == 1 & plomin[i,3] == 1 & plomin[i,11] == 0) That was my cut & paste error from trying out many different solutions! Cheers, Jill On 25/03/2008 17:31, "Oliver Craig Bevan" <bevan at fas.harvard.edu> wrote: This may not fix it, but it seems as though you have an extra (or missing) bracket: ## if (plomin[i,7] == 1) & plomin[i,3] == 1 & plomin[i,11] == 0 ) ## the bracket at the end of the line does not seem to close an earlier one. Hope this helps a little. Hi all, We are working on our replication project and have loaded an SPSS file into R. We are attempting to select rows based on values of three variables. The first two have values of 1 and 2. We can easily select for the value of 1. The third variable has values of 0 and 1. When we try to select for any value (either 0 or != 1), we get an error message that reads: Error in if (plomin[i, 11] == TRUE) { : missing value where TRUE/FALSE needed This is what our code looked like: vec <- c() k <- 0 for(i in 1:nrow(plomin)){ if (plomin[i,7] == 1) & plomin[i,3] == 1 & plomin[i,11] == 0 ) { k <- k + 1 vec[k] <- i} } mat.corr.gesl <- plomin[vec,c(20,21)] Does anyone have any idea why we should be getting this message? Or, alternatively, is there a better way of selecting for values of our variables? Thanks! Best wishes, Jill and Jeremy (Hodgen) _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l -- Graduate Student Department of Government Harvard University Cambridge, MA _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l Dr Jeremy Hodgen Senior Lecturer in Mathematics Education King's College London Department of Education and Professional Studies Franklin-Wilkins Building Waterloo Bridge Wing 150 Stamford Street London SE1 9NH Tel: 020 7848 3102 Fax: 020 7848 3182 E-mail: jeremy.hodgen at kcl.ac.uk