Re: [Gretl-devel] Dealing with big(!) matrix

On Sun, 28 May 2017, Riccardo (Jack) Lucchetti wrote: > On Sun, 28 May 2017, Marcin Błażejowski wrote: > >> Hi, >> >> suppose I have really big vector/matrix (I mean 100000 or more rows and >> 1-2 cols) and I need to find out the position of certain value >> stored in >> the first column in this matrix (like iminc and imaxc but for an >> arbitrary value). The matrix is not sorted and it may systematically >> grow (new rows are added at the bottom). >> >> The question is: what is the numerical most effective may of doing >> this? > > Question: what if the value is repeated? > anyway: something like this? <hansl> n = 100000 a = mrandgen(i,1,1000,n,2) target = 365 column = 1 sel = a[,column] .= target c = selifr(seq(1,n)'~a, sel) print c </hansl>

------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti ------------------------------------------------------- _______________________________________________ Gretl-devel mailing list Gretl-devel(a)lists.wfu.edu http://lists.wfu.edu/mailman/listinfo/gretl-devel