[R] merge 2 data frame based on more than 2 variables

[Simon Blomberg]

Then instead of by, use by.x and by.y to specifiy the variable names 
separately for both data frames. See ?merge, especially the examples.

Wensui Liu wrote:
> what if the names are different in 2 data frames?
>
>
> On 8/14/06, Simon Blomberg <blomsp at ozemail.com.au> wrote:
>   
>> Wensui Liu wrote:
>>     
>>> Dear Lister,
>>>
>>> I understand merge() can be used to join 2 data frames based on 1 variable.
>>> But how about merge based on more than 2 variables?
>>>
>>> Thank you so much!
>>>
>>>
>>>       
>> Just specify the 2 (or more) variable names in a column vector for "by")
>>
>> merge(dat1, dat2, by= c("VarA", "VarB"))
>>
>> assuming both data frames have columns VarA and VarB.
>>
>> --
>> Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat.
>> Centre for Resource and Environmental Studies
>> The Australian National University
>> Canberra ACT 0200
>> Australia
>> T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au
>> F: +61 2 6125 0757
>> CRICOS Provider # 00120C
>>
>>
>>     
>
>
>   


-- 
Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat.
Centre for Resource and Environmental Studies
The Australian National University
Canberra ACT 0200
Australia
T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au
F: +61 2 6125 0757
CRICOS Provider # 00120C