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From |
"David Merriman" <dmerrim@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Thu, 22 May 2008 16:46:51 -0500 |

Thanks. Actually, I just did not know this was an option. This seems even simpler than Scott's elegant little mata program. I really appreciate the help and will try it this way. On 5/22/08, Sergiy Radyakin <serjradyakin@gmail.com> wrote: > 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/ > -- David Merriman dmerrim@gmail.com * * 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/

**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>

**Re: st: need mata or perhaps egen help***From:*"Sergiy Radyakin" <serjradyakin@gmail.com>

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