Another approach: x[1:length(x) %% 10 == 0] <- NA
Just replace 10 by the interval you want. Or to add 5 missing values randomly: x[sample(1:length(x), 5)] <-NA ------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Rainer Schuermann Sent: Thursday, April 25, 2013 5:45 AM To: r-help@r-project.org Cc: Roslina Zakaria Subject: Re: [R] Missing data I read your data into a dataframe > x <- read.table( "clipboard" ) and renamed the only column > colnames( x )[1] <- "orig" With a loop, I created a 2nd column "miss" where in every 10th row the observation is set to NA: for( i in 1 : length( x$orig ) ) { if( as.integer( rownames( x )[ i ] ) %% 10 == 0 ) { x$miss[i] <- NA } else { x$miss[i] <- x$orig[i] } } This is probably the least elegant of all possible solutions but it works... Rgds, Rainer On Wednesday 24 April 2013 23:41:21 Roslina Zakaria wrote: > Dear r-users, > > I would like to investigate about how to fill in missing data. I started with a complete data and try to introduce missing data into the data series. Then I would use some method to fill in the missing data and then compare with the original data how good it is. My question is, how do I introduce missing data in my complete data systematically like for example every 10th data will be erased and assumed as missing. Here are some rainfall data: > > 125 > 130.3 > 327.2 > 252.2 > 33.8 > 6.1 > 5.1 > 0.5 > 0.5 > 0 > 2.3 > 0 > 0 > 0 > 0 > 0 > 0 > 0 > 0 > 0 > 0.8 > 5.1 > 0 > 0.3 > 0 > 0 > 0 > 0 > 0 > 0 > 45.7 > 43.4 > 0 > 0 > 0 > 0 > 0 > > Thank you so much for any help given. I hope my question is clear. > [[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.
