>>>>> "RobMcG" == McGehee, Robert <robert.mcge...@geodecapital.com> >>>>> on Tue, 29 Jun 2010 10:46:06 -0400 writes:
RobMcG> I came across the below mis-feature/bug using match with POSIXlt objects RobMcG> (from strptime) in R 2.11.1 (though this appears to be an old issue). >> x <- as.POSIXlt(Sys.Date()) >> table <- as.POSIXlt(Sys.Date()+0:5) >> length(x) RobMcG> [1] 1 >> x %in% table # I expect TRUE RobMcG> [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE >> match(x, table) # I expect 1 RobMcG> [1] NA NA NA NA NA NA NA NA NA RobMcG> This behavior seemed more plausible when the length of a POSIXlt object RobMcG> was 9 (back in the day), however since the length was redefined, the RobMcG> length of x no longer matches the length of the match function output, RobMcG> as specified by the ?match documentation: "A vector of the same length RobMcG> as 'x'". RobMcG> I would normally suggest that we add a POSIXlt method for match that RobMcG> converts x into POSIXct or character first. However, match does not RobMcG> appear to be generic. Below is a possible rewrite of match that appears RobMcG> to work as desired. RobMcG> match <- function(x, table, nomatch = NA_integer_, incomparables = NULL) RobMcG> .Internal(match(if(is.factor(x)||inherits(x, "POSIXlt")) RobMcG> as.character(x) else x, RobMcG> if(is.factor(table)||inherits(table, "POSIXlt")) RobMcG> as.character(table) else table, RobMcG> nomatch, incomparables)) RobMcG> That said, I understand some people may be very sensitive to the speed RobMcG> of the match function, yes, indeed. I'm currently investigating an alternative, considerably more programming time, but in the end should loose much less speed, is to .Internal()ize the tests in C code, so that the resulting R code would simply be match <- function(x, table, nomatch = NA_integer_, incomparables = NULL) .Internal(x, table, nomatch, incomparables) Martin Maechler, ETH Zurich RobMcG> and may prefer a simple change to the ?match RobMcG> documentation noting this (odd) behavior for POSIXlt. RobMcG> Thanks, Robert RobMcG> R.version RobMcG> _ RobMcG> platform x86_64-unknown-linux-gnu RobMcG> arch x86_64 RobMcG> os linux-gnu RobMcG> system x86_64, linux-gnu RobMcG> status RobMcG> major 2 RobMcG> minor 11.1 RobMcG> year 2010 RobMcG> month 05 RobMcG> day 31 RobMcG> svn rev 52157 RobMcG> language R RobMcG> version.string R version 2.11.1 (2010-05-31) RobMcG> Robert McGehee, CFA RobMcG> Geode Capital Management, LLC RobMcG> One Post Office Square, 28th Floor | Boston, MA | 02109 RobMcG> Tel: 617/392-8396 Fax:617/476-6389 RobMcG> mailto:robert.mcge...@geodecapital.com >> This e-mail, and any attachments hereto, are intended for use by the RobMcG> addressee(s) only and may contain information that is (i) confidential RobMcG> information of Geode Capital Management, LLC and/or its affiliates, RobMcG> and/or (ii) proprietary information of Geode Capital Management, LLC RobMcG> and/or its affiliates. If you are not the intended recipient of this RobMcG> e-mail, or if you have otherwise received this e-mail in error, please RobMcG> immediately notify me by telephone (you may call collect), or by e-mail, RobMcG> and please permanently delete the original, any print outs and any RobMcG> copies of the foregoing. Any dissemination, distribution or copying of RobMcG> this e-mail is strictly prohibited. RobMcG> ______________________________________________ RobMcG> R-devel@r-project.org mailing list RobMcG> https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel