[R] Data frame self-join with no duplicates

[Xin Zhang]

Thanks Dennis.  I will explore that.

On Mon, Sep 27, 2010 at 7:45 AM, Dennis Murphy <djmuser at gmail.com> wrote:
> Hi:
>
> One option is to read your data frame into R and then use your SQL code in
> conjunction with the sqldf package. It uses SQLite as its engine.
>
> HTH,
> Dennis
>
>
> On Mon, Sep 27, 2010 at 4:29 AM, Xin Zhang <xin.zhang at gmail.com> wrote:
>>
>> Suppose I have the following data frame (df):
>>
>> Year    Price
>> -------------------
>> 2001    10
>> 2002    20
>> 2003    30
>>
>> I would like to produce another data frame like this:
>>
>> a.Year    a.Price    b.Year    b.Price
>> ----------------------------------------------------
>> 2002    20    2001    10
>> 2003    30    2001    10
>> 2003    30    2002    20
>>
>> In SQL, this can be done as
>>
>> select a.*, b.*
>> from df as a, df as b
>> where a.Year > b.Year
>>
>> How do I do this efficiently in R?
>>
>> Many thanks.
>>
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>
>