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Questions tagged [nearest-neighbors]

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1
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0answers
148 views

Use of Morton Key to reduce number of grid points

I asked a question on Stack Overflow Performance Issue with VP Trees and Nearest Neighborsand I was not satisfied with the answer and so I thought I would reword my question for this site and post ...
0
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2answers
79 views

Effective way to build the neighbor's list in MD

I'm trying to implement the following form of the cell/neighbor list method in my MD code. I have divided my simulation box into a fixed number of cells, and according to its positions, I have ...
3
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1answer
70 views

MD Simulation: Reference for the Neighbor's List Method

With a rather basic knowledge in C++, I have written my own MD simulation code. Currently, I calculate forces in the most naive way: I go through all the atoms and account for their interactions. This ...
2
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2answers
60 views

Efficient Representation of (spatially sparse) spatial time series

Background I have a huge dataset consisting of points (on a plane) together with a timestamp for each point. This is a collection of car GPS measures, giving us the location (latitude/longitude) of ...
6
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2answers
2k views

Performance of kd-tree vs brute-force nearest neighbor search on GPU?

I wonder if there is any study that compares the performance of kd-tree vs brute-force nearest neighbor search on GPU. Post #4 on this page suggests that kd-tree may not be the optimal algorithm for ...
3
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1answer
605 views

Nearest Neighbors in radius via Z-order order curve?

Given a $M\times M\times M$ 3D cube grid $C$, how can I map the 3D grid-coordinates to 1D coordinates such that every cell's nearest neighbors can be represented by a continuous range of corresponding ...
1
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0answers
194 views

How to choose (and many) threshold in Eigenface?

I edited my question trying to make it as short and precise. I am developing a prototype of a facial recognition system for my Graduation Project. I use Eigenface and my main source is the document ...
2
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2answers
565 views

Finding nearest neighbors using Jaccard distance for positive, real-valued vectors

Say we have $x_i, \ldots, x_n \in R ^ D$ with positive, real components and use Jaccard distance $d(x_i, x_j) = 1 - \frac{\sum_{d = 1}^D\min(x_i^d, x_j^d)}{\sum_{d = 1}^D\max(x_i^d, x_j^d)}$ to find $...
4
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1answer
114 views

Numerically compute one-to-one mapping

I have a set of points defined by their coordinates $(x_1,y_1)$ after changing some parameters of the problem I obtain a second set of points defined by their coordinates $(x_2, y_2)$. There exists a ...
0
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1answer
168 views

Find closest Point based on orientation and Euclidean distance

I have a set of points P1(x1,y1), P2(x2,y2), P3(x3,y3), P4(x4,y4), P5(x5,y5) in the Cartesian plane. I am trying to find the closest point to P1 based on the ...
3
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1answer
2k views

Fast nearest neighbor search, Latitude Longitude

Is there a fast nearest neighbor search algorithm that generates the nearest neighbors, not based on Euclidean distances but based on geographic distances over a set of latitudes/longitudes. The fast ...
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5answers
630 views

Repeated nearest neighbor calculation for millions of data points too slow

I have a dataset running into millions of data points in 3D. For the calculation I am doing, I need to calculate neighbor (range search) to each data point in a radius, try to fit a function, ...
2
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1answer
211 views

$k$-Nearest Neighbor Search using examples

I want to perform $k$-Nearest Neighbor Search in multidimensional space, but not using for example $L_2$-distance. I want the user to specify some "similar"-pairs examples and then perform a search ...
5
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2answers
1k views

$k$ nearest neighbors for $n$ points with periodic boundary conditions in R^3

Take $n$ points ${\bf r} =\{ r_1 = (x_1,y_1,z_1), r_2=(x_2,y_2,z_2) \ldots r_n=(x_n,y_n,z_n) \}$ enclosed in a periodic box of length $L$, such that that the point $(0,0,0)=(L,0,0)$, $(0,0,0)=(L,L,L)$,...