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From |
"Sergiy Radyakin" <serjradyakin@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: need mata or perhaps egen help |

Date |
Thu, 22 May 2008 17:32:43 -0400 |

Dear David, is there any reason you don't want to multiply matrices in Stata? matrix R=DT*EDI Best regards, Sergiy Radyakin On 5/22/08, Scott Merryman <scott.merryman@gmail.com> wrote: > You can use -st_data()- and -st_store()- to move data between Stata > and mata (see -help m4_stata- ) > > Below is one way: > > clear > //nearest neighbor matrix > set obs 20 > set seed 12345 > forv i = 1/20 { > qui gen v`i' = uniform()<.2 in `i'/l > qui replace v`i' = 0 in `i' > } > mata: dist = makesymmetric(st_data(.,.)) > mata: dist > drop v* > > //spending > set obs 20 > gen spending = uniform() > gen total =. > > //total spending of neighbors > mata > spend = st_data(.,"spending") > spend > X = dist*spend > st_store(.,"total", X) > end > l > > > Scott > > On Thu, May 22, 2008 at 3:06 PM, David Merriman <dmerrim@gmail.com> wrote: > > I have a set of 584 communities and a square (584x584) matrix D that > > measures the > > distance from each community to each community. > > > > For each community I also have (584x1) vector (EDI) containing a > > variable that measures (essentially) the total amount spent on > > economic development incentives. > > > > I have this data for a number of years but I do not think that is > > important to my programming issues. > > > > For each of my communities I want a single variable that measures the > > total amount spent within a given distance (say 15 miles) on economic > > development incentives. > > > > I can convert my D matrix into a zero/1 matrix > > (assign zero to home community and and any community more than 15 > > miles distant, 1 otherwise) and Call this DT > > > > Seems I should be then be able to use mata to do the matrix multiplication > > > > R=DT*EDI > > > > R should be a 584x1 vector with the variable I need. > > > > > > The problem (I think) is that I have never used mata and am having a > > hard time figuring out how to feed my stata data into mata, do the > > multiplication and get the result back to stata. > > > > Can anyone tell me how to do this? > > Maybe there is an easier way to do it with egen or some other stata commands. > > > > Thanks > > Dave Merriman > > > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: need mata or perhaps egen help***From:*"David Merriman" <dmerrim@gmail.com>

**References**:**st: need mata or perhaps egen help***From:*"David Merriman" <dmerrim@gmail.com>

**Re: st: need mata or perhaps egen help***From:*"Scott Merryman" <scott.merryman@gmail.com>

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