Re: st: Generating a vector

[Phil Schumm <pschumm@uchicago.edu>]

On May 20, 2006, at 1:07 AM, Gauri Khanna wrote:
> I would like to generate an 1 x n vector, (n=326 rows) for cross  
> sectional data. This is actually an input price vector.
>
> I would then want to fill it with three or four input prices that I  
> have computed elsewhere. Hence the same value for each of the  
> inputs will be repeated 326 times.

I don't understand; if the vector is 1 x 326, and if each value will  
be repeated 326 times, then you'll need 4 separate vectors to hold  
the 4 values, no?



> I guess the first step would be to generate an empty(?)/null vector  
> and then fill it with values for each of the inputs.

I'm sorry, but there's really not enough here to give much of an  
answer.  If you want to generate a matrix containing a constant  
value, then you want to use the function J(), like so:


. mat a = J(1,5,23)

. mat li a

a[1,5]
    c1  c2  c3  c4  c5
r1  23  23  23  23  23


Note that -help matrix- (followed by clicking on "matrix functions")  
would have also given you this answer.  So, the first "meta-answer"  
to your question is really a suggestion that if you want to work with  
matrices in Stata, you should spend some time with [P] matrix.

In addition, it looks as though your immediate question is just the  
first step in what is really a larger problem you are trying to  
tackle.  If this is true, then it is really better to ask "I'm trying  
to do X and I think Y is a good place to start, but I'm having  
problems" rather than just asking "I can't figure out how to do Y".   
There are at least two reasons for this.  First, Y may not be the  
best way to start, so you should give people on the list an  
opportunity to tell you that; after all, getting you started on the  
right path is half the battle.  Second, if you are having problems  
with Y, there's a good chance you will also have problems with  
subsequent steps, and it's a lot more efficient for everyone involved  
if you just give your whole problem up front and let people help you  
with the entire thing.  Moreover, this makes for much more useful  
list archives (i.e., those who come along later with the same problem  
will be able to find the answer in a single posting or two, instead  
of spread across many).

That said, your question suggests that you are working on a economic  
problem, and not being an economist, I'm afraid others may need to  
help you solve it (but I too will read their answers and learn).  I  
apologize to the economists on the list for having volunteered your  
services ;)


-- Phil

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