st: Populating variables based upon integer value in the observation

[Mathew Wilkins <MWilkins@unfccc.int>]

Dear Stata listers,
I am wondering if it is possible to populate a certain number of variables
based upon san integer variable in the observation.  I am still relatively
new to stata and would relatively easily be able to program this in Access
or Excel.


I have variables a, b and yr1-yr10 (all integer)


I would like some commands that will populate variable b into variables
yr1-yr10, the number of the variables yr1-yr10 that are populated is based
upon variable a.  The below example dataset show an example of what I would
like to populate
                                                                                          
    obs |  a  |   b  |  yr |  yr2 |  yr |  yr4  |  yr5 |  yr6 |  yr7 |  yr8 |  yr |  yr1  
        |     |      |  1  |      |  3  |       |      |      |      |      |  9  |   0   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     1  |  4  |  25  |  25 |  25  |  25 |   25  |   0  |   0  |   0  |   0  |  0  |   0   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     2  |  10 |   3  |  3  |   3  |  3  |   3   |   3  |   3  |   3  |   3  |  3  |   3   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     3  |  7  |  19  |  19 |  19  |  19 |   19  |  19  |  19  |  19  |   0  |  0  |   0   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     4  |  1  |  14  |  14 |   0  |  0  |   0   |   0  |   0  |   0  |   0  |  0  |   0   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     5  |  9  |   5  |  5  |   5  |  5  |   5   |   5  |   5  |   5  |   5  |  5  |   0   
  ------+-----+------+-----+------+-----+-------+------+------+------+------+-----+------ 
     6  |  8  |  79  |  79 |  79  |  79 |   79  |  79  |  79  |  79  |  79  |  0  |   0   
                                                                                          








I have managed to use a forvalues loop to create the variables yr1-yr10 and
another loop to then populate them.


forvalues x = 1/10 {
gen yr`x' = 0
		if `x'<= a {
			replace yr`x' = b
		}
}

However the yr columns that are being populated are only based on variable
a in the first observation (result set below).

a	b	yr1	yr2	yr3	yr4	yr5	yr6	yr7	yr8	yr9	yr10
4	25	25	25	25	25	0	0	0	0	0	0
10	3	3	3	3	3	0	0	0	0	0	0
7	19	19	19	19	19	0	0	0	0	0	0
1	14	14	14	14	14	0	0	0	0	0	0
9	5	5	5	5	5	0	0	0	0	0	0
8	79	79	79	79	79	0	0	0	0	0	0

I have tried to use an additional forvalues loop for the observation
however this either does not work or take too long to process (the full
scale dataset I am working on is approximately 11,000 observations and the
yr columns go from 1 – 30.

Many thanks in advance for your time and consideration.

Regards
Mathew Wilkins
United Nations Climate Change Secretariat (UNFCCC)

Mathew Wilkins
Statistical Assistant
Strategy & Policy Development

(Embedded image moved to file: pic02220.gif)

United Nations
Climate Change Secretariat
Martin-Luther-King Strasse 8
53175 Bonn, Germany

Phone +49 228 815 1864
Fax +49 228 815 1999
mwilkins@unfccc.int
unfccc.int

Attachment: pic02220.gif
Description: GIF image