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{"@context":"https://schema.org","@type":"QAPage","mainEntity":{"@type":"Question","name":"How to do point point look up in arrayfire's array?","text":"
Let say, I have a 3d array called f
\nmat = f(x,y,z)
\nI want to look up from a list of points (x0,y0,z0).....(xn,yn,zn);
\nby spliting it up into
\narr_x = x0, x1, ....xn;
\narr_y = y0, y1,....yn;
\narr_z = z0, z1.... zn;
\n
I want to get the output like
\noutput = f(arr_x, arr_y, arr_z)
\n
Since arr_x, arr_y, arr_z are random points, I have difficult to use \"lookup\",  \"locate\", \"view!\",  \"index_gen\", \"assign_seq\" to generate the \"output\" without converting the array \"f\" to a 1d array.
\n
The following code will not work as of my expectation because view! will do a permutation mapping of xs and ys. It will expand the dimension of output instead of doing point to point lookup.
\n
Thank in advance for your help.
\n
Eli
\n
\nuse arrayfire::*;\n\nfn main() {\n    let (h, w, ch) = (4, 2, 3);\n    let x = range::<i32>(dim4!(1, w), 1);\n    let y = range::<i32>(dim4!(h), 0);\n    let z = range::<i32>(dim4!(1, 1, ch), 2);\n    let xs = tile(&x, dim4!(h));\n    let ys = tile(&y, dim4!(1, w));\n    let zs = tile(&z, dim4!(h, w, 1));\n\n    af_print!(\"xs=\", &xs);\n    af_print!(\"ys=\", &ys);\n    af_print!(\"zs=\", &zs);\n    let out = view!(zs[xs, ys]);\n    af_print!(\"out=\", &out);\n\n}\n
","upvoteCount":1,"answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"
should use \"approx1\"
","upvoteCount":1,"url":"https://github.com/arrayfire/arrayfire-rust/discussions/342#discussioncomment-3546048"}}}