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,

However if needs must..

Mike

On 28 June 2011 14:39, David Winsemius <dwinsemius@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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>>
>
> David Winsemius, MD
> West Hartford, CT
>
>

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