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Re: st: Re: Unix stata big dataset


From   ncdcta00@uniroma2.it
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Re: Unix stata big dataset
Date   Fri, 30 Nov 2007 09:37:30 +0100

Dear Michael,

1) You say you have 18 million observations -- is that for both
datasets or just one dataset?  How many observations are in the smaller
dataset?
in just one, in the other I have 2 million.

2) In your example data, do you expect to have 3 observations for id=1,
or 9 observations (all combinations of the 3 observations in each
dataset)?  If you want three observations, how do you tell which
observations to match from each dataset?
I use the id that is the same in each data set, and I use the option unmatched( master) in joinby command.



3) Do you want all observations for both datasets, or are there many
observations in the larger dataset that don't match and you don't need?
I need all the observations.

Thanks a lot.
Michael Blasnik


----- Original Message ----- From: <ncdcta00@uniroma2.it>
To: <statalist@hsphsun2.harvard.edu>
Sent: Thursday, November 29, 2007 5:36 PM
Subject: Re: st: Re: Unix stata big dataset


The memory that I can allocate is 15 gb, the total observations are 18 millions

I have duplicate observation but I can't drop because they are the spell of work for each person, and I need these observations.
The two dataset have in common the same id, so I need to match the data set in booth but id is not unique.

so, one data set is
id x1 x3 x 4...
1 0 1991 1998
1 1 1991 1998
1 2 1999 1999
2
and second is:
id y1 y2 y3
1 34 2 35
1 34 2 67
1 34 1 68
2

the idea is to keep all the people that have the same id to obtainer this data set
id xi x2 x3 y1 y2 y3
1............
1.................
2...........


Sorry I don't understand the last part of email , how to do the merge
thanks a lot for your help
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Catia Nicodemo



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