From pkensche at cmbi.ru.nl  Wed Nov 28 09:25:31 2007
From: pkensche at cmbi.ru.nl (pkensche at cmbi.ru.nl)
Date: Wed, 28 Nov 2007 09:25:31 +0100 (CET)
Subject: [Rd] hash access to data.frame uses prefix? (PR#10474)
Message-ID: <20071128082531.9DEC62834156@mail.pubhealth.ku.dk>

Full_Name: Philip Kensche
Version: R version 2.5.0 (2007-04-23)
OS: Linux
Submission from: (NULL) (131.174.146.31)


I want to access a row of a data.frame() by using the row names as hash keys.
This works fine for most keys.

Now consider the following data.frame().

> x <- data.frame(v=c(V40="a", V411="b"))

> x
     v
V40  a
V411 b

If I query for "V41", which does not exist in the data.frame() the call does not
return NA as I would expect but the row "V411".

> x[ "V41", ]
[1] b
Levels: a b

If there the prefix is not unique the query does not return a results, i.e.

> x <- data.frame(v=c(V412="a", V411="b"))

> x
     v
V412 a
V411 b

> x[ "V41", ]
[1] <NA>
Levels: a b


sessionInfo() output:
> sessionInfo()
R version 2.5.0 (2007-04-23)
i686-pc-linux-gnu

locale:
LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=en_US;LC_COLLATE=en_US;LC_MONETARY=en_US;LC_MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US;LC_IDENTIFICATION=C

attached base packages:
[1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  "methods"
[7] "base"

other attached packages:
 lattice
"0.15-4"



[Rd] hash access to data.frame uses prefix? (PR#10474)
pkensche at cmbi.ru.nl