Thanks a lot, Jim. I am not sure what difference the various POSIXes make - in the end, you are replacing a datetime hour with a numeric value, e.g., 1 or 9. That does not work for me, unfortunately.
> g = head(x) > dput(g) structure(list(price = c(500L, 500L, 501L, 501L, 500L, 501L), size = c(221000L, 2000L, 1000L, 13000L, 3000L, 3000L), src = c("R", "R", "R", "R", "R", "R"), t = structure(c(1104829224.133, 1104829247.096, 1104829272.139, 1104829278.142, 1104829330.721, 1104829348.713), class = c("POSIXt", "POSIXct"), tzone = ""), d = structure(list(sec = c(0, 0, 0, 0, 0, 0), min = c(0L, 0L, 0L, 0L, 0L, 0L), hour = c(0L, 0L, 0L, 0L, 0L, 0L), mday = c(4L, 4L, 4L, 4L, 4L, 4L), mon = c(0L, 0L, 0L, 0L, 0L, 0L), year = c(105L, 105L, 105L, 105L, 105L, 105L), wday = c(2L, 2L, 2L, 2L, 2L, 2L), yday = c(3L, 3L, 3L, 3L, 3L, 3L), isdst = c(0L, 0L, 0L, 0L, 0L, 0L)), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst"), class = c("POSIXt", "POSIXlt")), h = c(9, 9, 9, 9, 9, 9), m = structure(list( sec = c(0, 0, 0, 0, 0, 0), min = c(0L, 0L, 1L, 1L, 2L, 2L), hour = c(9L, 9L, 9L, 9L, 9L, 9L), mday = c(4L, 4L, 4L, 4L, 4L, 4L), mon = c(0L, 0L, 0L, 0L, 0L, 0L), year = c(105L, 105L, 105L, 105L, 105L, 105L), wday = c(2L, 2L, 2L, 2L, 2L, 2L), yday = c(3L, 3L, 3L, 3L, 3L, 3L), isdst = c(0L, 0L, 0L, 0L, 0L, 0L)), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst"), class = c("POSIXt", "POSIXlt")), s = structure(list(sec = c(24, 47, 12, 18, 10, 28), min = c(0L, 0L, 1L, 1L, 2L, 2L), hour = c(9L, 9L, 9L, 9L, 9L, 9L), mday = c(4L, 4L, 4L, 4L, 4L, 4L), mon = c(0L, 0L, 0L, 0L, 0L, 0L), year = c(105L, 105L, 105L, 105L, 105L, 105L), wday = c(2L, 2L, 2L, 2L, 2L, 2L), yday = c(3L, 3L, 3L, 3L, 3L, 3L), isdst = c(0L, 0L, 0L, 0L, 0L, 0L)), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst" ), class = c("POSIXt", "POSIXlt"))), .Names = c("price", "size", "src", "t", "d", "h", "m", "s"), row.names = c(NA, 6L ), class = "data.frame") > n = sqldf("select distinct h, src, count(*) from g group by h, src") Error in sqliteExecStatement(con, statement, bind.data) : RS-DBI driver: (error in statement: no such table: g) In addition: Warning message: In value[[3L]](cond) : RAW() can only be applied to a 'raw', not a 'double' -- View this message in context: http://r.789695.n4.nabble.com/Failure-to-aggregate-tp2528613p2533189.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.