I encountered surprising (to me, at least) behavior while using 'hours()' in package 'chron.' I will be grateful if someone can point out my error or provide an explanation and intuitive solution (I suppose I could convert chron to a character vector and use substring, but I deal mostly with newbies and kludgy approaches don't inspire much confidence).
I used 2.3.0 to construct the dataframe below. 1) 'date.char' is a character vector 2) 'time.char' is a character vector 3) 'chron' was created by >chron(dates(date.char),times(time.char)) 4) hours were extracted with >hours(chron). 5) Note that the hours used to construct 'chron' do not match the hours extracted with 'hours()' when minutes and seconds are "00:00." date.char time.char chron hour 1 09/20/06 00:00:00 (09/20/06 00:00:00) 0 2 09/20/06 01:00:00 (09/20/06 01:00:00) 0 3 09/20/06 02:00:00 (09/20/06 02:00:00) 2 4 09/20/06 03:00:00 (09/20/06 03:00:00) 3 5 09/20/06 04:00:00 (09/20/06 04:00:00) 3 6 09/20/06 05:00:00 (09/20/06 05:00:00) 5 7 09/20/06 06:00:00 (09/20/06 06:00:00) 6 8 09/20/06 07:00:00 (09/20/06 07:00:00) 6 9 09/20/06 08:00:00 (09/20/06 08:00:00) 8 10 09/20/06 09:00:00 (09/20/06 09:00:00) 9 11 09/20/06 10:00:00 (09/20/06 10:00:00) 9 12 09/20/06 11:00:00 (09/20/06 11:00:00) 11 13 09/20/06 12:00:00 (09/20/06 12:00:00) 12 14 09/20/06 13:00:00 (09/20/06 13:00:00) 12 15 09/20/06 14:00:00 (09/20/06 14:00:00) 14 16 09/20/06 15:00:00 (09/20/06 15:00:00) 15 17 09/20/06 16:00:00 (09/20/06 16:00:00) 15 18 09/20/06 17:00:00 (09/20/06 17:00:00) 17 19 09/20/06 18:00:00 (09/20/06 18:00:00) 18 20 09/20/06 19:00:00 (09/20/06 19:00:00) 18 21 09/20/06 20:00:00 (09/20/06 20:00:00) 20 22 09/20/06 21:00:00 (09/20/06 21:00:00) 21 23 09/20/06 22:00:00 (09/20/06 22:00:00) 21 24 09/20/06 23:00:00 (09/20/06 23:00:00) 23 This behavior is problematic if one wants to extract hours and use them to group data. Regards, Glen Sargeant ______________________________________________ [email protected] 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.
