Simpler: dat1$adj_mean <- within(dat1, ave(mean, point, FUN = function(x)x-x[1]))
ave() is a very handy function for this sort of thing. within() saves typing. -- Bert On Sat, Jun 30, 2012 at 4:16 PM, arun <smartpink...@yahoo.com> wrote: > HI, > > Try this: > #dat1: data > > dat2<-split(dat1,dat1$point) > adjmeanlist<-lapply(dat2,function(x)x[,3]-x[,3][1]) > dat3<-data.frame(dat1,adjmean=unlist(adjmeanlist)) > head(dat3) > point time mean sd adjmean > 1 1 1 52.50100 1.5073927 0.000000 > 3 1 2 54.50182 0.8510329 2.000818 > 4 1 3 56.60174 1.5787222 4.100739 > 5 1 4 57.20000 1.2292726 4.699000 > 6 1 5 59.30000 2.2632327 6.799000 > 7 1 6 57.80089 1.4745218 5.299893 > > > > A.K. > > > > ----- Original Message ----- > From: Kristiina Hurme <kristiina.hu...@uconn.edu> > To: r-help@r-project.org > Cc: > Sent: Saturday, June 30, 2012 5:21 PM > Subject: [R] How to adjust the start of a series to zero? (i.e. subtract > the first value from the sequence) > > Hello, > I'd have a time series, where I am plotting the means and sd of a distance > for a variety of positions along a bird's bill. I'd like to set each line > (represented by "point") to start at zero, so that I can look at the > absolute change along the series. At the moment I only know how to do that > in Excel, by subtracting the value of time 1, point 1 from all other times > for point 1. My actual data set has many points ( 20 per bird, only 3 shown > here), so I would love to make this faster in R. Ideally, I would have > another column titled "adj_mean" for the adjusted means. > > Here is an example. > > > sort2v4 > point time mean sd > 1 1 1 52.501000 1.5073927 > 3 1 2 54.501818 0.8510329 > 4 1 3 56.601739 1.5787222 > 5 1 4 57.200000 1.2292726 > 6 1 5 59.300000 2.2632327 > 7 1 6 57.800893 1.4745218 > 8 1 7 55.303508 2.2661855 > 9 1 8 51.100943 1.8540025 > 10 1 9 50.600000 1.7126977 > 2 1 10 52.904716 1.1010460 > 111 2 1 50.605963 1.2633969 > 113 2 2 52.203828 0.7890765 > 114 2 3 54.100909 1.1013344 > 115 2 4 55.000000 1.1547005 > 116 2 5 57.001725 1.6341500 > 117 2 6 55.003591 1.5652438 > 118 2 7 52.911089 1.7373914 > 119 2 8 49.204022 1.0350809 > 120 2 9 48.904103 0.8747568 > 112 2 10 50.915700 0.8765483 > 131 3 1 48.608228 0.8433913 > 133 3 2 49.307101 0.4827703 > 134 3 3 51.310824 0.9424023 > 135 3 4 52.413350 0.6997860 > 136 3 5 54.116723 1.1927297 > 137 3 6 52.618161 1.1686288 > 138 3 7 49.822764 1.6303473 > 139 3 8 47.107336 1.2013356 > 140 3 9 47.104214 1.1986148 > 132 3 10 48.719484 0.6765047 > > and I would like it to look like this... (which I did in Excel). The start > of each time 1-10 has an adj_mean of 0. > > sort2v4 > point time mean sd adj_mean > 1 1 1 52.501 1.5073927 0 > 3 1 2 54.501818 0.8510329 2.000818 > 4 1 3 56.601739 1.5787222 4.100739 > 5 1 4 57.2 1.2292726 4.699 > 6 1 5 59.3 2.2632327 6.799 > 7 1 6 57.800893 1.4745218 5.299893 > 8 1 7 55.303508 2.2661855 2.802508 > 9 1 8 51.100943 1.8540025 -1.400057 > 10 1 9 50.6 1.7126977 -1.901 > 2 1 10 52.904716 1.101046 0.403716 > 111 2 1 50.605963 1.2633969 0 > 113 2 2 52.203828 0.7890765 1.597865 > 114 2 3 54.100909 1.1013344 3.494946 > 115 2 4 55 1.1547005 4.394037 > 116 2 5 57.001725 1.63415 6.395762 > 117 2 6 55.003591 1.5652438 4.397628 > 118 2 7 52.911089 1.7373914 2.305126 > 119 2 8 49.204022 1.0350809 -1.401941 > 120 2 9 48.904103 0.8747568 -1.70186 > 112 2 10 50.9157 0.8765483 0.309737 > 131 3 1 48.608228 0.8433913 0 > 133 3 2 49.307101 0.4827703 0.698873 > 134 3 3 51.310824 0.9424023 2.702596 > 135 3 4 52.41335 0.699786 3.805122 > 136 3 5 54.116723 1.1927297 5.508495 > 137 3 6 52.618161 1.1686288 4.009933 > 138 3 7 49.822764 1.6303473 1.214536 > 139 3 8 47.107336 1.2013356 -1.500892 > 140 3 9 47.104214 1.1986148 -1.504014 > 132 3 10 48.719484 0.6765047 0.111256 > > Thank you so much for your help. > Kristiina > > -- > View this message in context: > http://r.789695.n4.nabble.com/How-to-adjust-the-start-of-a-series-to-zero-i-e-subtract-the-first-value-from-the-sequence-tp4634999.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. > -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm [[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.
