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# Re: st: Relative Comparision between Observations

 From Nick Cox <[email protected]> To [email protected] Subject Re: st: Relative Comparision between Observations Date Thu, 25 Aug 2011 15:52:23 +0100

```With that number, "my" approach can't get its shoes on, let alone run
down the track -- although it is I think what you asked for.

I think you really need advice from people who do your kind of thing
in Stata, but unfortunately I am not one of them. I only have two
broad thoughts: think long not wide, and at some point -merge- will be

Nick

On Thu, Aug 25, 2011 at 3:43 PM,  <[email protected]> wrote:
> Hi Nick,
> thanks a lot.
> The dataset contains 500 000 transactions (in addition to the 7 million spreads), but I will use your approach as a starting point for an algorithm that allows to cope with this large dataset.
>
> Any suggestion to get this done quickly is still very welcome.
>
>
> Best regards and thanks again,
>
> Jens
>
>
>
>
>
>
>
> -------- Original-Nachricht --------
>> Datum: Thu, 25 Aug 2011 15:20:58 +0100
>> Von: Nick Cox <[email protected]>
>> An: [email protected]
>> Betreff: Re: st: Relative Comparision between Observations
>
>> For -transaction[2]- (e.g.) you can generate
>>
>> . gen within_2 = inrange(transaction[2], start, end) & isspread
>>
>> Is the number of transactions small enough to allow a variable for
>> every one of them?
>>
>> If so, this is crude but should work
>>
>> forval i = 1/`=_N' {
>>      if isspread[`i'] == 0 gen within_`i' = inrange(transaction[`i'],
>> }
>>
>> A visceral reaction is that getting the wrong data structure is
>> horribly easy here, but people who work with this kind of data may be
>>
>> Nick
>>
>> On Thu, Aug 25, 2011 at 2:55 PM, Jens Kruk <[email protected]> wrote:
>> > Hi Nick,
>> > lets say the data looks like this:
>> >
>> > 1_____1___________3________6______.
>> > 2_____0___________.________.______5
>> > 3_____1___________2________5______.
>> > 4_____0___________.________.______5.5
>> >
>> >
>> >
>> > now what I want Stata to do is to tell me (for example by creating
>> additional variables that contain the ids) that ids 2 and 4 occured between
>> start and end date of observation 1 (5 and 5.5 are between 3 and 6) and that id
>> 2 occured between the start and end date of spread 3 (5 is weakly between
>> 2 and 5).
>> > A perfect result of the procedure would look like this:
>> >
>> > 1_____1___________3________6______.______________2_____4__
>> > 2_____0___________.________.______5______________._____.__
>> > 3_____1___________2________5______.______________2_____.__
>> > 4_____0___________.________.______5.5____________._____.__
>> >
>> >
>> > Best, Jens
>> >
>> >
>> >
>> >
>> > -------- Original-Nachricht --------
>> >> Datum: Thu, 25 Aug 2011 14:22:19 +0100
>> >> Von: Nick Cox <[email protected]>
>> >> An: [email protected]
>> >> Betreff: Re: st: Relative Comparision between Observations
>> >
>> >> Please show a representative chunk of your data so that precisely what
>> >>
>> >> Nick
>> >>
>> >> On Thu, Aug 25, 2011 at 2:09 PM,  <[email protected]> wrote:
>> >>
>> >> > I want to perform the following task for a very large dataset (so
>> >> writing a Mata loop is probably not the solution): the dataset consists
>> of two
>> >> sorts of data: spreads and transactions. Spreads do have a start and an
>> end
>> >> date, while transactions only have a transaction date. Now I want to
>> know
>> >> whether some transaction happend between the start and end date of a
>> >> Ideally, I would like to have variables containing all the ids of
>> >> transactions that occured between the start and end data of the spread
>> for each
>> >> spread. Is there a way to use inexact matching or merging for this ?
>> >> > This should be a familiar problem, however, I do not have a clue how
>> to
>> >> solve it.
>>
>> *
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>
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```

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