Hi all, I have data size of :
> dim(sample) [1] 35943 17 The first column is "stdate" - is date ( 01/11/2009 00:00:00,02/11/2009 00:00:00,02/11/2009 00:00:00 etc... ) Login is 13th column - is numbers (12,0,1 erc...) The below operation return the following error. > sample1 <- read.csv(file="sample1.csv",sep=",",header=TRUE) > avglog <- with(sample1, tapply(Login, stdate, mean)) Warning messages: 1: In mean.default(X[[1L]], ...) : argument is not numeric or logical: returning NA 2: In mean.default(X[[2L]], ...) : argument is not numeric or logical: returning NA 3: In mean.default(X[[3L]], ...) : argument is not numeric or logical: returning NA 4: In mean.default(X[[4L]], ...) : argument is not numeric or logical: returning NA 5: In mean.default(X[[5L]], ...) : argument is not numeric or logical: returning NA 6: In mean.default(X[[6L]], ...) : argument is not numeric or logical: returning NA 7: In mean.default(X[[7L]], ...) : argument is not numeric or logical: returning NA > avglog 01/11/09 00:00 02/11/09 00:00 03/11/09 00:00 04/11/09 00:00 05/11/09 00:00 NA NA NA NA NA How to fix this issue? Thanks & Rg Mohan L [[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.