[R] Subsetting vector with preserved order

[Hervé Pagès]

Hi

On 01/02/2014 04:04 PM, arun wrote:
> Hi,
> Try ?match
>   b[match(d,a)]
> #[1] "Joe"  "Bob"  "Dick"

Or use 'a' to put names on 'b':

   > names(b) <- a
   > b
         A       B       C       D       E
     "Tom"  "Dick" "Harry"   "Bob"   "Joe"

Then subset by names:

   > b[d]
        E      D      B
    "Joe"  "Bob" "Dick"

Cheers,
H.


> A.K.
>
>
> I have three vectors as follows:
>
>> a <- c('A','B','C','D','E')
>> b <- c('Tom','Dick','Harry','Bob','Joe')
>> d <- c('E','D','B')
>
> Subsetting b by using d on a, with b[a %in% d], gives the names in the order they appear in b:
>
>>   b[a %in% d]
>> [1] "Dick" "Bob"  "Joe"
>
> But I'd like them to show in the order in d, as "Joe" "Bob" "Dick". What is the easy way to do this?
>
> Thanks.
>
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-- 
Hervé Pagès

Program in Computational Biology
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