[R] Converting unique strings to unique numbers

[Hervé Pagès]

Hi Kate,

I found that matching the character vector to itself is a very
effective way to do this:

   x <- c("a", "bunch", "of", "strings", "whose", "exact", "content",
          "is", "of", "little", "interest")
   ids <- match(x, x)
   ids
   # [1]  1  2  3  4  5  6  7  8  3 10 11

By using this trick, many manipulations on character vectors can
be replaced by manipulations on integer vectors, which are sometimes
way more efficient.

Cheers,
H.


On 05/29/2015 09:58 AM, Kate Ignatius wrote:
> I have a pedigree file as so:
>
> X0001 BYX859      0      0  2  1 BYX859
> X0001 BYX894      0      0  1  1 BYX894
> X0001 BYX862 BYX894 BYX859  2  2 BYX862
> X0001 BYX863 BYX894 BYX859  2  2 BYX863
> X0001 BYX864 BYX894 BYX859  2  2 BYX864
> X0001 BYX865 BYX894 BYX859  2  2 BYX865
>
> And I was hoping to change all unique string values to numbers.
>
> That is:
>
> BYX859 = 1
> BYX894 = 2
> BYX862 = 3
> BYX863 = 4
> BYX864 = 5
> BYX865 = 6
>
> But only in columns 2 - 4.  Essentially I would like the data to look like this:
>
> X0001 1 0 0  2  1 BYX859
> X0001 2 0 0  1  1 BYX894
> X0001 3 2 1  2  2 BYX862
> X0001 4 2 1  2  2 BYX863
> X0001 5 2 1  2  2 BYX864
> X0001 6 2 1  2  2 BYX865
>
> Is this possible with factors?
>
> Thanks!
>
> K.
>
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-- 
Hervé Pagès

Program in Computational Biology
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