Make the question reproducible (I used dput after getting the data into a dataframe). You need to provide a date of origin for the as.Date function. Try lubridate package.
library(lubridate) wells <- structure(list(ID = structure(c(3L, 3L, 2L, 1L, 3L, 2L, 3L, 1L, 1L, 2L, 3L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L), .Label = c("BC-0002", "BC-0003", "BC-0004"), class = "factor"), Date = c(41163L, 41255L, 41345L, 41351L, 41355L, 41438L, 41438L, 41443L, 41521L, 41522L, 41522L, 41627L, 41627L, 41634L, 41703L, 41703L, 41710L, 41795L, 41795L, 41801L, 41905L, 41905L, 41906L), DepthtoWater_bgs = c(260.6, 261.65, 166.58, 317.85, 262.15, 167.55, 265.45, 317.25, 321.25, 168.65, 266.15, 168.95, 265.25, 312.31, 169.25, 265.05, 313.01, 168.85, 266.95, 330.41, 169.75, 267.75, 321.01), test = 3:25, test2 = 1:23), .Names = c("ID", "Date", "DepthtoWater_bgs", "test", "test2"), class = "data.frame", row.names = c("1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23")) wells$year <- year(as.Date(wells$Date, origin = '1900-1-1')) head(wells$year) Mark R. Mark Sharp, Ph.D. Director of Primate Records Database Southwest National Primate Research Center Texas Biomedical Research Institute P.O. Box 760549 San Antonio, TX 78245-0549 Telephone: (210)258-9476 e-mail: msh...@txbiomed.org > On Mar 8, 2015, at 12:50 AM, Steve Archambault <archste...@gmail.com> wrote: > > Hi all, > > I am trying in vain to create a new object "Year" in my data frame from > existing Date data. I have tried many different approaches, but can't seem > to get it to work. Here is an example of some code I tried. > > date1<- as.Date(wells$Date,"%m/%d/%Y") > wells$year<-as.numeric(format(date1, "%Y")) > > I am starting with data that looks like this. > > ID Date DepthtoWater_bgs test test2 > 1 BC-0004 41163 260.60 3 1 > 2 BC-0004 41255 261.65 4 2 > 3 BC-0003 41345 166.58 5 3 > 4 BC-0002 41351 317.85 6 4 > 5 BC-0004 41355 262.15 7 5 > 6 BC-0003 41438 167.55 8 6 > 7 BC-0004 41438 265.45 9 7 > 8 BC-0002 41443 317.25 10 8 > 9 BC-0002 41521 321.25 11 9 > 10 BC-0003 41522 168.65 12 10 > 11 BC-0004 41522 266.15 13 11 > 12 BC-0003 41627 168.95 14 12 > 13 BC-0004 41627 265.25 15 13 > 14 BC-0002 41634 312.31 16 14 > 15 BC-0003 41703 169.25 17 15 > 16 BC-0004 41703 265.05 18 16 > 17 BC-0002 41710 313.01 19 17 > 18 BC-0003 41795 168.85 20 18 > 19 BC-0004 41795 266.95 21 19 > 20 BC-0002 41801 330.41 22 20 > 21 BC-0003 41905 169.75 23 21 > 22 BC-0004 41905 267.75 24 22 > 23 BC-0002 41906 321.01 25 23 > > Any help would be greatly appreciated! > > -Steve > Sent from my iPhone > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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 -- To UNSUBSCRIBE and more, see 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.