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Find matrix location of the nearest point?

Xiaxing Xiong

Posted 4 years ago

1) How to find the matrix location of the nearest point? Nearest[{{2,1},{2,3},{3,4},{4,5},{5,6}.......{4,9}},{3,5}] 2)if I have a original set of points ospts={{2,1},{2,3},{3,4},{4,5},{5,6}.......{4,9}}, and a target set of points tspts={{1,2}....{3,5}}. For each target point I like to find the nearest original point and its position within the ospts. How should I do it? Thanks. Xiaxing

POSTED BY: Xiaxing Xiong

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Rohit Namjoshi

Posted 4 years ago

Hi John, What do you mean by List[] operation Your proposed solution Apply[(Nearest[opt, #])&, tpt] will just return a single point. How does it answer the first question or the second question?

POSTED BY: Rohit Namjoshi

Anonymous User

Posted 4 years ago

Mathematica's Help for Nearest shows examples of nearly the same thing. I'm unsure why you are asking how to find the nearest. If you want the nearest to a set of points you could say "at the center of a set" or "on the boundary of a set". but you appear to be asking for merely the nearest of each of one to the other which can be done by List[] operation. Apply[ (Nearest[ opt, #])&, tpt] a statistical approach might also be interesting

POSTED BY: Anonymous User

Rohit Namjoshi

Posted 4 years ago

Hi Xiaxing, Here is one way to do it SeedRandom[123]; ospts = RandomInteger[25, {10, 2}]; tspts = RandomInteger[25, {10, 2}]; closest = tspts // Map[First@Nearest[ospts, #] &]; ListPlot[{ospts, tspts}, PlotLegends -> {"ospts", "tspts"}, Epilog -> {Red, Transpose[{closest, tspts}] // Map[Line]}, ImageSize -> Large] Positions of the closest points positions = closest // Map[Position[ospts, #] &] // Flatten (* {1, 8, 1, 7, 1, 7, 2, 4, 4, 9} *)

Hi Xiaxing,

Here is one way to do it

SeedRandom[123];
ospts = RandomInteger[25, {10, 2}];
tspts = RandomInteger[25, {10, 2}];
closest = tspts // Map[First@Nearest[ospts, #] &];

ListPlot[{ospts, tspts},
 PlotLegends -> {"ospts", "tspts"},
 Epilog -> {Red, Transpose[{closest, tspts}] // Map[Line]},
 ImageSize -> Large]

enter image description here

Positions of the closest points

positions = closest // Map[Position[ospts, #] &] // Flatten
(* {1, 8, 1, 7, 1, 7, 2, 4, 4, 9} *)

POSTED BY: Rohit Namjoshi

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