[R] how to combine two data frames via factors (or somehow else)

[Philipp Chapkovski]

Thank you very much for your help - everybody, and especially Joshua!

On Mon, May 30, 2011 at 1:21 AM, Joshua Wiley <jwiley.psych at gmail.com> wrote:
> Hi Philipp,
>
>
> ## Read in your data
> ## posting the output of dput() would have made our lives easier
> d1 <- read.table(textConnection("x y
> 1 a X
> 2 b X
> 3 c X
> 4 f Z
> 5 e Z
> 6 g Z"), header = TRUE, row.names = 1)
> d2 <- read.table(textConnection(" y1 y2
> 1  X W
> 2  Z W"), header = TRUE, row.names = 1)
> closeAllConnections()
>
> ## Solution using merge()
> dboth <- merge(d1, d2, by.x = "y", by.y = "y1")
>
> ## an alternate solution in this case
> d1.alt <- d1
> d1.alt$owner <- d2[d2$y1[d1$y], "y2"]
>
> ## Compare them
> dboth
> d1.alt
>
> Hope this helps,
>
> Josh
>
> On Sun, May 29, 2011 at 1:51 PM, Philipp Chapkovski
> <chapkovski at gmail.com> wrote:
>> Hello!
>> The question should be very naive, but I am a beginner and stuck with
>> this unfortunately.
>> There is a dataset of people's affiliation to companies that looks
>> like that (a data frame actually)
>>  x y
>> 1 a X
>> 2 b X
>> 3 c X
>> 4 f Z
>> 5 e Z
>> 6 g Z
>> where x is a name of a person and y is a company name. That is, a,b,c
>> work in a company X. f,e,g work in a company Z.
>>
>> and there is another dataset with the affiliation of companies. Like
>> that (much much longer in reality):
>>  y1 y2
>> 1  X W
>> 2  Z W
>> that means that both X and Z belongs to the same company W.
>> What is the most compact way (without loops etc) to 'attach' the 'head
>> company' from the second dataset to the first dataset so I can have
>> something like:
>>
>>  x  y owner
>> 1 a X W
>> ...
>> 4 f  Z W
>>
>> I know it should be done somehow with factors, but I don't know how.
>> Thank you in advance!
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Joshua Wiley
> Ph.D. Student, Health Psychology
> University of California, Los Angeles
> http://www.joshuawiley.com/
>