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From |
adiallo5@worldbank.org |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: RE: Minimum of a vector or a matrix. |

Date |
Fri, 11 Nov 2005 10:51:11 -0500 |

Thanks Nick for the answers. Indeed, mata is a great tool worth learning. However, I do not get exactly what I want. It is giving me "values" while I want "conditions at the place of occurrences". I've got: 1 2 3 +-------------+ 1 | 1 1 3 | 2 | 1 1 3 | 3 | 1 1 3 | +-------------+ while I wanted: 1 2 3 +-------------+ 1 | 1 0 1 | 2 | 0 0 1 | 3 | 0 1 0 | +-------------+ I tried to dig a little bit, but am not yet familiar with looping in mata. clear mata: A = (1,2,3\1,2,3\3,1,5) r = cols(A) B = colmin(A)\colmin(A)\colmin(A) J = J(r,r,0) A r B J for (i=1;i<=r;++i { J(i,j) = cond([A(i,j)==colmin(A),1,0) } J I keep getting a conformability error. Many thanks in advance. Amadou. ------------------------------------------------------------------------------------------------- I'll take these questions in different order. Nick n.j.cox@durham.ac.uk adiallo5@worldbank.org > Suppose the macro: > local mymacro 1 2 3 4 5 6 7 8 9 0 > how to localise and index the smallest value of the macro? > I checked with macrolists but there is no answer. numlist "`mymacro'", sort local min : word 1 of `r(numlist)' > Is there a way to get the minimum value of a vector or a matrix? mata: ------------------------------------------------- mata (type end to exit) -------------------- : m = (1,2,3\4,5,6\7,8,9) : min(m) 1 : rowmin(m) 1 +-----+ 1 | 1 | 2 | 4 | 3 | 7 | +-----+ : colmin(m) 1 2 3 +-------------+ 1 | 1 2 3 | +-------------+ > Suppose : > > > A[3,3] > c1 c2 c3 > r1 0 2 3 > r2 1 2 3 > r3 3 1 5 > > I want to have: > > B[3,3] > c1 c2 c3 > r1 1 0 1 > r2 0 0 1 > r3 0 1 0 > > where the 1s are true if the value in column j is the smallest. : m :== (rowmin(m), rowmin(m), rowmin(m)) 1 2 3 +-------------+ 1 | 1 0 0 | 2 | 1 0 0 | 3 | 1 0 0 | +-------------+ : m :== (colmin(m) \ colmin(m) \ colmin(m)) 1 2 3 +-------------+ 1 | 1 1 1 | 2 | 0 0 0 | 3 | 0 0 0 | +-------------+ > Is there a way to combine (ie: the smallest value of the column > j AND of the corresponding line i)? This is one is left as an exercise. ------------------------------------------------------------------------------- * * 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/

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