Hi, Using the example data, library(zoo) z1 <- read.zoo("dfRaw_20140509.csv",sep="",index.column=2,format="%Y%m%d") z1 # P_num P_ID Totalvalue #2013-05-10 25193 1230238 1.203 #2013-05-24 25190 1230238 1.201 #2013-07-05 25191 1230238 1.208 #2013-08-02 25194 1230238 1.195 #2013-09-06 25192 1230238 1.209 #2013-09-20 915 1230238 1.124 #2013-10-25 17980 1230238 1.276 #2013-11-08 23316 1230238 1.431 #2013-11-29 3817 1230238 2.082 #2014-01-10 17901 1230238 1.053 #2014-01-24 23315 1230238 1.106 #2014-02-14 32554 1230238 1.493 #2014-03-14 23311 1230238 1.072 #2014-03-14 25885 1230238 1.000 #2014-03-21 32550 1230238 1.383 #2014-05-09 32551 1230238 1.309
time(z1)[8] <- "2013-10-28" format(time(z1), "%w") #[1] "5" "5" "5" "5" "5" "5" "5" "1" "5" "5" "5" "5" "5" "5" "5" "5" z1[format(time(z1), "%w") %in% 5,] A.K. The data loks like this P_num Date P_ID Totalvalue 1 00915 20130920 1230238 1.124 2 17901 20140110 1230238 1.053 3 17980 20131025 1230238 1.276 4 23311 20140314 1230238 1.072 5 23315 20140124 1230238 1.106 6 23316 20131108 1230238 1.431 7 25190 20130524 1230238 1.201 8 25191 20130705 1230238 1.208 9 25192 20130906 1230238 1.209 10 25193 20130510 1230238 1.203 11 25194 20130802 1230238 1.195 12 25885 20140314 1230238 1 13 32550 20140321 1230238 1.383 14 32551 20140509 1230238 1.309 15 32554 20140214 1230238 1.493 16 3817 20131129 1230238 2.082 I have used the ZOO package but still I am getting an error. Can you please help. library(zoo) z <- read.zoo("dfRaw_20140509.csv", header = TRUE, sep = ",",format = "%d-%b-%y",colClasses = c("numeric", "numeric", "character", "character", "numeric", "numeric")) z[format(time(z), "%w") %in% 2,] Error in `[.data.frame`(rval, , j) : undefined columns selected ______________________________________________ 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.