It looks like you already have the zoo package loaded so you can use its na.locf(), which replaces NA's with the last non-NA value. Convert the 0s to NAs with replace() and feed the result into na.locf(): a <- c(-2,0,0,0,1,0,0,3,0,0,-4) aOut <- c(-2,-2,-2,-2,1,1,1,3,3,3,-4) na.locf(replace(a, a==0, NA) ) # [1] -2 -2 -2 -2 1 1 1 3 3 3 -4 all.equal(aOut, .Last.value) # [1] TRUE
If you need to treat NA and 0 differently you will need to do more work. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of Raghuraman Ramachandran > Sent: Tuesday, July 10, 2012 8:23 AM > To: r-help@r-project.org > Subject: [R] Help with vectors and rollapply > > Hello > > I have a vector a =(-2,0,0,0,1,0,0,3,0,0,-4) > > I want to replace all zeros into previous non-zero state. So for instance the > above > vector should be converted into: > > a= (-2,-2,-2,-2,1,1,1,3,3,3,-4) > > I tried many things and finally concluded that probably(?) rollapply may be > the best > way? > > I tried > f= function(x){ > ifelse(x==0,Lag(x),x) > } > > And then, rollappy(a,1,f) and that didn't work. Can someone help please? > > Thx > R > > > Jefferies archives and monitors outgoing and incoming e-mail. The contents of > this > email, including any attachments, are confidential to the ordinary user of > the email > address to which it was addressed. If you are not the addressee of this email > you may > not copy, forward, disclose or otherwise use it or any part of it in any form > whatsoever. Since the confidentiality of Internet e-mail cannot be guaranteed, > please do not include private or confidential information (such as account > numbers) > or instructions requiring your authorization (such as orders or funds > transfers) in your > e-mail communication to us. This email may be produced at the request of > regulators > or in connection with civil litigation. Jefferies accepts no liability for > any errors or > omissions arising as a result of transmission. Although this transmission and > any > attachments are believed to be free of any virus or other defect that might > affect any > computer system into which it is received and opened, it is the! > responsibility of the recipient to ensure that it is virus free and no > responsibility is > accepted by Jefferies, its subsidiaries and affiliates, as applicable, for > any loss or > damage arising in any way from its use. In the United Kingdom, Jefferies > operates as > Jefferies International Limited; registered in England: no. 1978621; and > Jefferies > Bache Limited; registered in England: no. 114226; registered office for both: > Vintners > Place, 68 Upper Thames Street, London EC4V 3BJ. Jefferies International > Limited and > Jefferies Bache Limited are authorised and regulated by the Financial Services > Authority. If you received this transmission in error, please immediately > contact the > sender and destroy the material in its entirety, whether in electronic or > hard copy > format. Thank you. > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
