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Re: st: One varlist into a matrix with multiple columns


From   Sergiy Radyakin <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: One varlist into a matrix with multiple columns
Date   Wed, 14 Aug 2013 17:01:18 -0400

No he wants a matrix:

clear
set obs 10
gen i = _n
expand 10
bys i: gen j = _n
gen x = rnormal()

*** this is only one possible way of determining the matrix size ****
sum i
local rows=r(max)
sum j
local cols=r(max)
matrix M=J(`rows',`cols',.)
*********************************************************************

forval z=1/`=_N' {
  local tr=i[`z']
  local tc=j[`z']
  matrix M[`tr',`tc']=x[`z']
}

matrix list M


On Wed, Aug 14, 2013 at 4:48 PM, Scott Merryman
<[email protected]> wrote:
> Do you mean something like:
>
> clear
> set obs 10
> gen i = _n
> expand 10
> bys i: gen j = _n
> gen x = rnormal()
> reshape wide x , i(i) j(j)
> l
>
> Scott
>
>
> On Wed, Aug 14, 2013 at 3:15 PM, Samuel Bailey <[email protected]> wrote:
>> Hello,
>>
>> I have a dataset with three columns: the first two are the i and j
>> coordinates of a potential matrix, and the third is the data that
>> would go into the (i,j)th spot. Is there a way (in Stata or Mata) to
>> create a matrix directly from these three variables? I've tried using
>> -mkmat- to create a column vector which gets sent to Mata, where it's
>> looped through into a new matrix. However, as a column vector the data
>> exceeds the maximum matrix size in my version of Stata (though as a
>> square matrix it would not).
>>
>> Sincerely,
>> Sam Bailey
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