<>
Make sure you specify -double- as the type for the new variable:
*******
clear*
input itemid cityid1 cityid2
22 61 6
22 61 8
22 61 9
22 61 7
22 61 10
22 61 13
end
compress
gen double newid = 1000000*itemid + 1000*cityid1 + cityid2
list, noobs
*******
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Christopher
Hajzler
Sent: Sonntag, 6. Dezember 2009 20:47
To: [email protected]
Subject: st: problem creating unique identifier
Dear Statalist,
My version of Stata is doing something quite strange (Version 8.0
intercooled). I have several variables which are contained in
separate data files, and I want to merge them by creating a unique
identifier for each observation (over which I can sort the data - I
realize it is not strictly necessary to do it this way, but I thought
this method would help avoid errors). Each observation represents a
city pair (just over 100 cities), and an "item", and in each file I've
created the variable using the following command:
gen newid = 0
replace newid = 1000000*itemid + 1000*cityid1 + cityid2
For some reason Stata will only do a partial job - it seems to be
getting the itemid and cityid1 right when producing newid (the first 4
or 5 digits), and "almost" gets cityid2 right, assigning the correct
values every few observations but then incorrectly allocating the same
value to adjacent observations. For example, one file reads:
newid itemid cityid1 cityid2 var1
...
22061006 22 61 6 ...
22061008 22 61 8 ...
22061008 22 61 9 ...
22061008 22 61 7 ...
22061010 22 61 10 ...
22061012 22 61 13 ...
...
I have worked with much larger datasets, so I cannot imagine memory
allocation is an issue. Any other ideas?
Best wishes,
Chris
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