[R] Matching data to a new column

[Luc Villandre]

Hi Laura,

The function merge() works well, but another elegant to do it would 
involve match().

(Assuming your data.frame object is called x)
> x$motherAge <- with(x, age[match(mothers.I.D,I.D)])
Cheers,

-- 
*Luc Villandré*
/Biostatistician
McGill University Health Center -
Montreal Children's Hospital Research Institute/


John Kane wrote:
> x <- "I.D  age  'MID'
> 01     5       03
> 02     6       06
> 03     16     NA
> 04     8       06
> 05     3       NA
> 06     17     NA"
>     
> xx <- read.table(textConnection(x), header=TRUE); xx
> closeAllConnections()
>
> ag1 <- xx[, c(1,2)] ; ag1
> ag2 <- xx[, c(1,3)] ; ag2
> names(ag2[2]) <- "I.D"
>
> merge(ag1,ag2, by="I.D")
>
>
> --- On Fri, 6/26/09, Kubasiewicz, Laura <laura.kubasiewicz08 at imperial.ac.uk> wrote:
>
>   
>> From: Kubasiewicz, Laura <laura.kubasiewicz08 at imperial.ac.uk>
>> Subject: [R] Matching data to a new column
>> To: "r-help at r-project.org" <r-help at r-project.org>
>> Received: Friday, June 26, 2009, 6:55 AM
>>
>> Hi all,
>>
>> I wonder if anyone can help,
>>
>> I have a dataframe with columns for...
>>
>> 'I.D'  'age'  'mothers I.D'
>> 01     5   
>>    03
>> 02     6   
>>    06
>> 03     16     NA
>> 04     8   
>>    06
>> 05     3   
>>    NA
>> 06     17     NA
>>
>> I need to create a new column for 'mothers age' which puts
>> the age of the individual with 'mothers i.d' into the row
>> for her offspring (so individual 01 would have 16 in the
>> mothers age column, as thats the age of individual 03)
>>
>> Hope that makes sense, any help appreciated,
>>
>> Thanks
>> Laura
>>
>>     [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>>
>>     
>
>
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