Thank you, works perfectly.
On Wed, Mar 28, 2012 at 3:11 PM, David Winsemius <dwinsem...@comcast.net>wrote:
>
> On Mar 28, 2012, at 5:26 PM, Trevor Davies wrote:
>
> I've looked but I cannot find a more elegant solution.
>>
>> I would like to be able to scan through a data.frame and remove multiple
>> and various instances of certain contents.
>>
>> A trivial example is below. It works, it just seems like there should be
>> a
>> one line solution.
>>
>> #Example data:
>> a <-
>> data.frame(V1=1:3,V2=c(paste(**LETTERS[1],LETTERS[1:3],sep=''**
>> )),options(stringsAsFactors
>> = FALSE))
>>
>> #> a
>> # V1 V2
>> #1 1 AA
>> #2 2 AB
>> #3 3 AC
>>
>> #Cumbersome solution (which would be even more cumbersome with real data)
>>
>> indices.of.aa <- which(a$V2 %in% "AA")
>> indices.of.ab <- which(a$V2 %in% "AB")
>> indices.of.ac <- which(a$V2 %in% "AC")
>> a$V2 <- replace(a$V2, indices.of.aa, "c")
>> a$V2 <- replace(a$V2, indices.of.ab, "d")
>> a$V2 <- replace(a$V2, indices.of.ac, "e")
>>
>>
> Use match:
>
> > df1 <- data.frame(V1=1:3,V2=c(paste(**LETTERS[1],LETTERS[1:3],sep=''**
> )),
> stringsAsFactors = FALSE))
> > unique(df1$V2)
> [1] "AA" "AB" "AC"
> > df1$new <- c("c","d","e")[match(df1$V2, unique(df1$V2))]
> > df1
> V1 V2 new
> 1 1 AA c
> 2 2 AB d
> 3 3 AC e
>
>
>
> ## output
>> #> a
>> # V1 V2
>> #1 1 c
>> #2 2 d
>> #3 3 e
>>
>> I know with the trivial example above there are extremely simple solutions
>> but my data.frame is a few thousand rows.
>> Thanks all.
>> Trevor
>>
>> [[alternative HTML version deleted]]
>>
>
>
> ---
> David Winsemius, MD
> West Hartford, CT
>
>
[[alternative HTML version deleted]]
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