Nuno Prista

2011-Feb-21 16:22 UTC

### [R] assign value to multiple objects with a given ls pattern

Dear R colleagues, This seems pretty straight forward but I have been banging my head on this for some time and can't seem to find a solution suppose I have something like a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4 I would like to quickly assign to objects with a certain pattern, e.g., those in ls(pattern="a") a specific value, e.g., "99", without having to assign each object at a time. is there a way I can do this within a "for" cycle? I have tested several eval and parse statements but with no success. Regards, Nuno Prista ____________________________ PhD student Instituto de Oceanografia Faculdade de Ci?ncias da Universidade de Lisboa Campo Grande, Lisboa, 1749-016 Lisboa, Portugal

Ista Zahn

2011-Feb-21 16:55 UTC

### [R] assign value to multiple objects with a given ls pattern

Hi Nuno, Yes, you can do for(i in ls(pattern="a")) { assign(i, 99) } but honestly this is a bad idea. It will try to assign the value of 99 to any object in your workspace that contains an a, which sounds really scary to me. Better I think to use a list: ab.list <- list(a1=1, a2=2, a3=3, a4=4, b1=3, b2=4) ab.list[grep("a", names(ab.list))] <- 99 Or even just a named vector ab.vector <- c(a1=1, a2=2, a3=3, a4=4, b1=3, b2=4) ab.vector[grep("a", names(ab.vector))] <- 99 Best, Ista On Mon, Feb 21, 2011 at 4:22 PM, Nuno Prista <nmprista at fc.ul.pt> wrote:> Dear R colleagues, > > This seems pretty straight forward but I have been banging my head on this for some time and can't seem to find a solution > > suppose I have something like > > a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4 > I would like to quickly assign to objects with a certain pattern, e.g., those in > > ls(pattern="a") > > a specific value, e.g., "99", without having to assign each object at a time. > > is there a way I can do this within a "for" cycle? I have tested several eval and parse statements but with no success. > > Regards, > > Nuno Prista > > ____________________________ > PhD student > Instituto de Oceanografia > Faculdade de Ci?ncias da Universidade de Lisboa > Campo Grande, Lisboa, > 1749-016 Lisboa, > Portugal > > ______________________________________________ > R-help at 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. >-- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org

Ivan Calandra

2011-Feb-21 16:57 UTC

### [R] assign value to multiple objects with a given ls pattern

Hi, This works for me: pat <- ls(pattern="^a") ## I would anchor "a" to the beginning with "^" for safety! for (i in seq_along(pat))assign(pat[i], value=99) Or this with lapply: lapply(pat, FUN=function(x) assign(x, value=99, envir=.GlobalEnv)) See ?assign HTH, Ivan Le 2/21/2011 17:22, Nuno Prista a ?crit :> Dear R colleagues, > > This seems pretty straight forward but I have been banging my head on this for some time and can't seem to find a solution > > suppose I have something like > > a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4 > I would like to quickly assign to objects with a certain pattern, e.g., those in > > ls(pattern="a") > > a specific value, e.g., "99", without having to assign each object at a time. > > is there a way I can do this within a "for" cycle? I have tested several eval and parse statements but with no success. > > Regards, > > Nuno Prista > > ____________________________ > PhD student > Instituto de Oceanografia > Faculdade de Ci?ncias da Universidade de Lisboa > Campo Grande, Lisboa, > 1749-016 Lisboa, > Portugal > > ______________________________________________ > R-help at 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. >-- Ivan CALANDRA PhD Student University of Hamburg Biozentrum Grindel und Zoologisches Museum Abt. S?ugetiere Martin-Luther-King-Platz 3 D-20146 Hamburg, GERMANY +49(0)40 42838 6231 ivan.calandra at uni-hamburg.de ********** http://www.for771.uni-bonn.de http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php

Greg Snow

2011-Feb-21 17:18 UTC

### [R] assign value to multiple objects with a given ls pattern

If instead of having a1, a2, etc. as global variables you put them into a list then this becomes simple. The general rule is that if you ever want to do the same (or similar) think to a set of variable, then they should not have been separate variables, but part of a bigger one. Lists work well for this (there are other possibilities as well, but lists cover most of the cases). -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow at imail.org 801.408.8111> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of Nuno Prista > Sent: Monday, February 21, 2011 9:22 AM > To: r-help at R-project.org > Subject: [R] assign value to multiple objects with a given ls pattern > > Dear R colleagues, > > This seems pretty straight forward but I have been banging my head on > this for some time and can't seem to find a solution > > suppose I have something like > > a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4 > I would like to quickly assign to objects with a certain pattern, e.g., > those in > > ls(pattern="a") > > a specific value, e.g., "99", without having to assign each object at a > time. > > is there a way I can do this within a "for" cycle? I have tested > several eval and parse statements but with no success. > > Regards, > > Nuno Prista > > ____________________________ > PhD student > Instituto de Oceanografia > Faculdade de Ci?ncias da Universidade de Lisboa > Campo Grande, Lisboa, > 1749-016 Lisboa, > Portugal > > ______________________________________________ > R-help at 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.