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From |
Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: re matrix substitution |

Date |
Sat, 22 Aug 2009 16:33:15 +0100 |

While Scott's reply is valid, it will only take care of negative values and not arbitrary thresholds. Here is a one-liner using the -mm_cond()- function in Ben Jann's superb -moremata- package (SSC): ************************ mata thresh = 3 A = (1, 2, 3\ 9, 8, 1) mm_cond(A :>= J(rows(A), cols(A), thresh), A, J(rows(A), cols(A), 0)) end ************************ T On Sat, Aug 22, 2009 at 4:13 PM, Scott Merryman<scott.merryman@gmail.com> wrote: > It might be easier to do something like: > > mata > A = 1,2,3 \ -1, -2, -3 \ 5,6,-9 > A > C = (A + abs(A))/2 > C > end > > > Scott > > > On Sat, Aug 22, 2009 at 4:52 AM, Marwan > Elkhoury<elkhoury.marwan@gmail.com> wrote: >> dear statalist, >> >> sorry to bother you with this minor pblm but I'm not familiar with the >> stata mata environment , more familiar with the matlab matrix >> environment. anyway, I wish to substitute some matrix factor loadings >> which are negative or small to zero and keep the others identical. >> Now, I've written naively some piece of codes to do that and it's not >> working, either because I'm not writing the pgm correctly or not >> saving it correctly in the right place or not calling the function >> correctly; so the codes are for stata 10 version and are the following: >> >> /* matrix substitution */ >> >> program mysubsi >> version 10 >> syntax varname [if] [in] >> marksample touse >> mata: mysubsi(string st_matrix("A"), "`touse'") >> display as txt " C = " as res r(C) >> end >> >> >> capture mata mata drop mysubsi() >> mata >> real matrix mysubsi(real matrix A, real scalar thresh) >> { >> real scalar r, c >> real matrix C >> r=rows(A) >> c=cols(A) >> for(i=1;i<=r;i++) { >> for(j=1;j<=c;j++) { >> if (A[i,j]< thresh) { >> C[i,j] =0 >> } >> else { >> C[i,j] = A[i,j] >> } >> } >> } >> return(C) >> } >> >> mata mosave mysubsi(), dir(c:\ado\personal\m) replace >> end >> >> /// end of pgm >> >> then I try to call the function, writing: >> mata: mysubsi("A", "`touse'") >> mata: mysubsi("entering the real matrix function which I want to >> perform change upon", thresh number) >> >> I'm surely missing on something and any help would be greatly >> appreciated. >> >> sincerely yours, >> >> Marwan > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > -- To every ω-consistent recursive class κ of formulae there correspond recursive class signs r, such that neither v Gen r nor Neg(v Gen r) belongs to Flg(κ) (where v is the free variable of r). * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: re matrix substitution***From:*Marwan Elkhoury <elkhoury.marwan@gmail.com>

**Re: st: re matrix substitution***From:*Scott Merryman <scott.merryman@gmail.com>

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