Ricardo,
Thank you very much for your answer. It works perfectly too.
El sáb, 5 ago 2023 a las 4:37, Riccardo (Jack) Lucchetti (<
p002...@staff.univpm.it>) escribió:
> On 04/08/2023 20:24, Josué Martínez-Castillo wrote:
> > Thank you both, Artur and sven. Both approaches were very helpful. I
> > finally used:
> >
> >> _ _
> >> # mymatrix: column1 = income, column2 = frequency
> >> matrix mymatrix = {35, 5; 120, 5; 150, 0; 320, 6; 400, 5}
> >> matrix result = {}
> >> loop i=1..5
> >> result |= mshape(mymatrix[i,1], mymatrix[i,2], 1)
> >> endloop
> >> print mymatrix result
> >> _ _
> The best generalisation I could find to the 2-way (xtab) case is as
> follows:
>
> <hansl>
> set seed 1234567
>
> nr = 3
> nc = 2
>
> ### xtab case
>
> xt = mrandgen(i, 0, 6, nr, nc)
> tot = nr * nc
> result = zeros(sum(xt), 2)
> fin = 0
> loop j = 1 .. nc
> loop i = 1 .. nr
> x = xt[i,j]
> if x > 0
> ini = fin+1
> fin += x
> result[ini:fin,] = mshape({i,j}, 2, x)'
> endif
> endloop
> endloop
>
> print xt result
> </hansl>
>
> On the other hand, Sven's remark made me think that sometimes you might
> want to compute all possible indices of a arbitrarily-sized tensor. Once
> you have those, you can use them in a single loop without having to nest
> many.
>
> The function is:
>
> <hansl>
> function matrix indices(matrix dims)
>
> n = nelem(dims)
> if n == 0
> ret = {}
> elif n == 1
> ret = seq(1, dims[1])'
> else
> matrix a = indices(dims[-1])
> scalar d = dims[1]
> scalar m = rows(a)
> b = vec(mshape(seq(1,d), d, m)')
> a = ones(d,1) ** a
> ret = b ~ a
> endif
>
> return ret
> end function
> </hansl>
>
> So for example, you can create X = indices({2,3}), which would yield
>
> 1 1
> 1 2
> 1 3
> 2 1
> 2 2
> 2 3
>
> and loop over the rows of X instead of a nested loop construct such as
>
> <hansl>
> loop i = 1 .. 2
> loop j = 1 .. 3
> # do things
> endloop
> endloop
> </hansl>
>
> The nice thing is, the number of elements in the argument to the
> "indices" function is potentially unlimited. For example,
> indices({3,2,3}) returns
>
> 1 1 1
> 1 1 2
> 1 1 3
> 1 2 1
> 1 2 2
> 1 2 3
> 2 1 1
> 2 1 2
> 2 1 3
> 2 2 1
> 2 2 2
> 2 2 3
> 3 1 1
> 3 1 2
> 3 1 3
> 3 2 1
> 3 2 2
> 3 2 3
>
> Maybe we could add this to the extra addon?
>
>
>
>
>
>
> -------------------------------------------------------
> Riccardo (Jack) Lucchetti
> Dipartimento di Scienze Economiche e Sociali (DiSES)
>
> Università Politecnica delle Marche
> (formerly known as Università di Ancona)
>
> r.lucche...@univpm.it
> http://www2.econ.univpm.it/servizi/hpp/lucchetti
> -------------------------------------------------------
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