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From |
Austin Nichols <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Re: st: Matrices utilities, Basic calculations. When to start using Mata over Stata? |

Date |
Fri, 23 Apr 2010 09:58:47 -0400 |

Radaf paf <ladwen@hotmail.com>: You can loop in Stata and use Mata, or you can do rowsums by postmultiplying by a column vector of ones. e.g. forv n=1/10 { mata: st_matrix("a`n'",runiform(25,36)) mata: st_matrix("b`n'",runiform(25,36)) mat c`n'=J(25,1,.) } mat li a10 forv n=1/10 { mata: a=st_matrix("a`n'") mata: b=st_matrix("b`n'") mata: ra=a*J(cols(a),1,1) mata: rb=b*J(cols(a),1,1) mata: c=ra:*(ra:>rb) mata: st_matrix("c`n'",c) } forv n=1/10 { mata: ra=rowsum(st_matrix("a`n'")) mata: rb=rowsum(st_matrix("b`n'")) mata: c=ra:*(ra:>rb) mata: st_matrix("d`n'",c) } mat li c10 mat li d10 2010/4/23 Radaf paf <ladwen@hotmail.com>: > Hi all, > > I have a total of 20 matrices, A1-A10 and B1-B10 of size > 25x36 > > I am trying to do the sum of each row of the matrix A and > compare them with the sum of each row of the matrix B. Then I retain the > highest sum and put it in a new matrix, say C. > > The "rowsum" utility in Mata is appealing, but I couldn't figure out how to create > the loops ( no "foreach" command?), generate new matrixes names > automatically (for the matrices C) and access my 20 matrices within the > loops in Mata. > > Here is what I would do if I could use "rowsum" > in Stata: > > > foreach n in 1 2 3 4 5 6 7 8 9 10 {; > > > matrix c'n´= J(rowsof(A'n´),1,0) *I create my matrix c (vector of > 25 rows) containing only 0 values ; > > foreach i in 1-25 {; > * where i correspond to the number of rows; > > > > R_sum_A'n´=rowsum(A'n´) ; > R_sum_B'n´=rowsum(B'n´) ; > > > > *I compare the two sums and if the rowsum of A is bigger than B I > put it in the new matric C, if not I leave it equals to 0 ; > > > if el(R_sum_A'n´,'i´,1)> el(R_sum_B'n´,'i´,1) > > > matrix C'n´['i´,1] =el(R_sum_A'n´,'i´,1) ; > > > > > }; > }; > > > But I cannot use "rowsum" into stata . So what would you suggest ? > > Thanks a lot > > Raphael * * 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/

**Follow-Ups**:**st: Re: st: Re: st: Matrices utilities, Basic calculations. When to start using Mata over Stata?***From:*Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com>

**References**:**st: Matrices utilities, Basic calculations. When to start using Mata over Stata?***From:*Radaf paf <ladwen@hotmail.com>

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