On Jun 28, 2011, at 10:29 AM, Michael Pearmain wrote:
> Thanks for the idea David,
> My problem comes from having (say) upto 10 different match files, so
> nested ifelse whilst would work doesn't seem and elegant solution,
Well, you cannot mix text and numeric modes in a vector as you
appeared to expect.
There may be a limit on the nesting if ifelse's as well. ISTR "7" but
have not been able to document that vague memory.
It seems that separate matching runs followed by some logic that
cbind()-ed and then "collapsed" the results perhaps by just dropping
all the NA's row-wise.
--
David.
>
> However if needs must..
>
> Mike
>
> On 28 June 2011 14:39, David Winsemius <dwinsem...@comcast.net> wrote:
>
> On Jun 28, 2011, at 6:18 AM, Michael Pearmain wrote:
>
> Hi All,
>
> I'm having a few problems using match and a lookup table, previous
> Googling
> show numerous solutions to matching a lookup table to a dataset,
> My situation is slightly different as i have multiple lookup tables,
> (that i
> cannot merge - for integrity reasons) that i wish to match against
> my data,
> and each of these files is large, so lots of for / if conditions are
> not
> ideal. (withstanding that i have multiple files of course)
>
>
> For example,
> I have data:
>
> v <- c("foo", "foo", "bar", "bar", "baz")
> id <- c(1,2)
> id2 <- c(3)
> name <- c("foo", "bar")
> name2 <- c("baz")
> df1 <- data.frame(id, name)
> df2 <- data.frame(id2, name2)
>
> v <- df1$id[match(v,df1$name)]
> v
> [1] 1 1 2 2 NA
>
> A numeric vector.
>
>
> So here i actually want to return
> v
> [1] 1 1 2 2 "baz"
>
> Not possibly a numeric vector.
>
>
>
> so next time i can run
> v <- df2$id[match(v,df2$name)]
>
> and return:
> v
> [1] 1 1 2 2 3
>
> You need to keep track of the successful matches in df1 and then ypu
> probably want to interleave them with matches in df2. Perhaps
> instead use ifelse to do the work for you:
>
> > ifelse(!is.na(match(v,df1$name)), match(v,df1$name),
> match(v,df2$name2) )
>
> [1] 1 1 2 2 1
>
>
>
> Any help very much appreciated
>
> Mike
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
> David Winsemius, MD
> West Hartford, CT
>
>
David Winsemius, MD
West Hartford, CT
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