[R] Left Outer Join 2 DF's on Multiple Conditions

[Nikhil Kaza]

Look at sqldf package, it is easier to do sql like statements with it.

Nikhil Kaza
Asst. Professor,
City and Regional Planning
University of North Carolina

nikhil.list at gmail.com

On Jul 25, 2010, at 6:10 PM, harsh yadav wrote:

> Hi,
>
> I am trying to execute the following SQL statement using two data  
> frames:
>
> tab1, tab2 : Two Tables
>
> Select tab1.*, tab2.*, tab1.tobiiTime - tab2.ruiTime as timeDiff,
> IFNULL(n-m, -9999999) as alwaysIncrement
>                  FROM tab1
> LEFT OUTER JOIN tab2 On tab1.data1 - tab2.mouseX = 0 And tab1.data2 -
> tab2.mouseY = 0
>
>
> I am trying to do the following in R:-
>
> *#Getting error here:*
> data <- merge(tab1,tab2, all.x=TRUE, by=(data$data1 - data$mouseX ==  
> 0),
> by=(data$data2 - data$mouseY == 0))
> data <- cbind(data, data[, "tobiiTime"] - data[, "ruiTime"], data[,  
> "n"] -
> data[, "m"])
>
> #Change name of column tobiiTime-ruiTime to timeDiff, for convenience
> data <- rename(data, c(tobiiTime-ruiTime="timeDiff"))
>
> #Change name of column n-m to alwaysIncrement, for convenience
> data <- rename(data, c(n-m="alwaysIncrement"))
>
> *In the merge step, I want to include the following condition of  
> merging:-*
> tab1.data1 - tab2.mouseX = 0 And tab1.data2 - tab2.mouseY = 0
>
> Any ideas how this could be done.
>
> Thanks in advance.
>
> Regards,
> Harsh Yadav
>
> 	[[alternative HTML version deleted]]
>
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