R help - Mar 2013 - merge function while obviating duplicate columns XXXX

Hi everyone,

I have the following call to the merge() function. How does one
prevent duplicate columns in the resulting data frame that the 2
parent data frames have in common but are not true key or "by"
variables?


data3<-merge(data1,data2,by="id")
data3

id total.x total.y balance
1 78  78 90
2 91  91 63
3 74  74 57
4 89  89 58
5 90  90 27


In this example, total is not a true key or "by" variable that
uniquely identifies rows suitable for matching purposes, but instead
just happens to be common to both sets.

In reality, I have hundreds for these "in common" variables, so I need
a solution that is tractable for a large number of "in common"
columns.

Thanks!

Dan

On Mon, Mar 11, 2013 at 3:17 PM, Dan Abner <dan.abner99 at gmail.com>
wrote:
> Hi everyone,
>
> I have the following call to the merge() function. How does one
> prevent duplicate columns in the resulting data frame that the 2
> parent data frames have in common but are not true key or "by"
> variables?
>
>
> data3<-merge(data1,data2,by="id")
> data3
>
> id total.x total.y balance
> 1 78  78 90
> 2 91  91 63
> 3 74  74 57
> 4 89  89 58
> 5 90  90 27
>
>
> In this example, total is not a true key or "by" variable that
> uniquely identifies rows suitable for matching purposes, but instead
> just happens to be common to both sets.
Well, which one do you want? Or do you want to exclude total from the result?
>
> In reality, I have hundreds for these "in common" variables, so I
need
> a solution that is tractable for a large number of "in common"
> columns.
>
> Thanks!
>
> Dan
>
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