Questions tagged [nearest]

Questions on the usage of Nearest and creating a custom distance function for it; also on NearestNeighborGraph, RegionNearest, GeoNearest and related concepts.

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6
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1answer
43 views

NearestTo causes a kernel crash when applied to a list of SparseArrays [closed]

Nearest and NearestTo cause a kernel crash on Mathematica 12.0.0 for Mac OS X. (running on OS X 10.11.6) when operating on a list of SparseArray vectors. Here's my minimal breaking example: ...
2
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2answers
56 views

How to Create an Efficient Step Function from Data

I have list of rules from where a DateListStepPlot can be created to visualize the problem: ...
2
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2answers
172 views

Find the smallest and largest distance between two points distributed in 3D space

Suppose I have some 3D points, e.g. {{0, 0, 1}, {0, 0, 1.3}, {0, 1, 0}, {1.2, 0, 0}}. Now I want to find the smallest and largest distance between two points. A ...
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2answers
209 views

Efficient multicolor search

I'm hoping someone can help me improve the following fun code-snippet, which takes a target color and searches through a set of images to find the ones that most closely match: ...
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0answers
23 views
8
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2answers
161 views

Speeding up Nearest with multiple distance thresholds

Consider the following example of using Nearest: ...
14
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3answers
357 views

Is there a built-in function I can use to measure the similarity of two trees?

This is a higher level question, and I don't expect a full answer, but maybe a nudge in the right direction would help, or maybe there is a built in Mathematica function that does something very ...
4
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2answers
221 views

How to use Nearest as a lookup function?

I have data1 and a target point targetPts, and want to find the closest point from the data. As you can see from below, the 29th ...
8
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3answers
134 views

How to connect all points in a graph generated by a set of given vertexes?

I am trying to construct a tree by looking at the nearest neighbors (or just approximately nearest for higher efficient) of a set of given vertexes. I first try this:- ...
1
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0answers
59 views

Estimating Lyapunov exponent from a time series problem [duplicate]

I am trying to use this code for estimating L.e.: ...
6
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2answers
227 views

Find the element in a list of triples which has z-coordinate nearest a specified value

Here is my list coordinate {x,y,z} ...
1
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2answers
500 views

Finding the x-value corresponding to a y-value found using Nearest [closed]

I have a large 2d array of infinite precision named "data" of x values and y values. I am using Nearest to find the y-value closest to a specified number, say 0....
3
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0answers
108 views

Getting Distances from Nearest Function [closed]

I am fairly new to mathematica. I am trying to find a way to mock python's KDTree.query function in mathematica. Basically I have 9 vectors (each length two). I want to know the three closest vectors ...
4
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4answers
208 views

Forming tracks of coordinates depending on distance

I have a list that consists of certain number of coordinates sub-lists (here 8). (The following data are only an example to describe my problem.) ...
1
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1answer
103 views

Define a 3D surface for input in Region function

I am looking for the shortest distance from a 3D surface to a random point, and also for the exact point on the surface. These are the definitions and visualization. ...
5
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1answer
264 views

Nearest non-collinear/non-coplanar points

This is a long post. Most of it is just an introduction so the question itself is understandable. The question is in bold. Just skip to it if you want to hear the point. Everything below the question ...
2
votes
1answer
81 views

How can I get get index and distance in Nearest functions in Low Version [closed]

Nearest[{"I'm", "sorry", "Dave"} -> All, "David"] {<|"Element" -> "Dave", "Index" -> 3, "Distance" -> 2|>} However, in a WolframScript.wl file, ...
3
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1answer
338 views

Opposite of Nearest?

There is an useful function Nearest in Mathematica, which finds the element in the aggregate given as its 1st argument that is nearest to its 2nd argument. It is ...
1
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0answers
77 views

A question for Nearest [closed]

Assume that I want to get nearest 10 points of a thousand random points in a given area to original point in three-dimensional coordinate system. Does anyone know how the ...
1
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2answers
159 views

Using Nearest with periodic boundary conditions of a list

Take the list e = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} I want to get the nearest points but with a wraparound condition. So lets say I want to find the 5 nearest ...
4
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1answer
234 views

How to rapidly find the nearest pairs of points in different clusters

Background For speed up this question or this question,I have such need. Current try: Suppose I have $3$ clusters of points: ...
5
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1answer
147 views

How to find the index of a facet of a boundary mesh region closest to a given point?

Using the RegionNearest[] function, it is possible to calculate the point, $p_{mesh}$, on a mesh region that is nearest to some input point, $p_{input}$. My ...
3
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1answer
631 views

Better way to use Nearest

I'm trying to write a snippet of code that, given an input value (value), checks a list of arbitrary length (data) for the ...
1
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2answers
131 views

Finding Nearest Element to a line in a 2 dimensional Array

I have a 2-dimensional list of data of $x$ and $y$ coordinates. I am looking for a way to get the element of the list which has the closest $y$ value to a given $y$ value. I tried using ...
3
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3answers
222 views

Question about Nearest [duplicate]

In the following example Nearest finds the nearest values between list1 and list2 and ...
4
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3answers
657 views

Remove 2D points where nearest neighbor exceeds certain distance

I have the following 2D points: ...
5
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3answers
421 views

Mean distance beween nearest 2 coordinates

I have as an example the following 2d-coordinates: ...
4
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2answers
317 views

Tracing 2d coordinates by using Nearest function

In 5 digital images I have determined the 2d coordinates of detected objects. The resulting coordinate list can be downloaded from here: http://pastebin.com/7bE0CEJ5 ...
1
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3answers
211 views

Why won't DiscretizeRegion work with a custom distance function?

I am trying (in 10.0) to create a region from a list of data points. I have created myDistance to use as the boolean test for whether or not a point should be included in the region ...
4
votes
1answer
203 views

Draw lines between all neighbours

I have seen this question, but what I want is a bit different. I have a set of data (blue points) and I would like to end up with something like this: , i.e. joining each site with all its (nearest)...
1
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1answer
234 views

precision and speed inefficiency issues of Nearest function with sqrt expression [closed]

Recently, Nearest has been attacked for many bugs. Some are already fixed. I am going to show some issues when Nearest applied ...
4
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2answers
596 views

How to get Nearest lower value?

Nearestgives me the closest value to my reference, but what if I am always looking for the closest value, which is lower than my reference? ...
10
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1answer
223 views

Why does Nearest not support Sqrt?

Bug introduced in 10.0.2 and fixed in 10.3.0 Simple examples with two points nf1=Nearest[{{0, 0}, {Sqrt[2], Sqrt[2]}}] nf1[{0, 0}, {All, 2.1}] gives ...
15
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3answers
749 views

Cannot get nearest neighbors from Nearest

Bug introduced in 10 and fixed in 10.3 There still persists the failure to return 30.72 (another bug according to Daniel Lichtblau but from the developer's point of view it may be a feature). ...
10
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3answers
386 views

Using an ellipse as a threshold for Nearest function

The Nearest function can receive as a threshold parameter a radius to look for elements inside that. From the documentation: ...
4
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3answers
784 views

Find nearest distance of an interior point from perimeter

By definition, the interior point is a point inside an arbitrary region like this: In picture above, $y$ is an interior point of region. My question is how to find the distance of an interior point ...
7
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4answers
2k views

efficient way to give nearest neighbour and next nearest neighbour of every point in a point set

Suppose we have a point set, the points are labeled 1,2,3,....n. And p[i] is the coordinate of the point. Now I want the label of nearest and next nearest point (...
3
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1answer
425 views

Filtering a point cloud: How to reject some points in a 3D cloud of particles?

I'm having an issue with a 3D distribution of points. The distribution is really nice looking in Mathematica, but it is used in an OpenGL astronomy program (Celestia) to generate a nebula, with ...
9
votes
3answers
462 views

Manually specifying distance metric to Nearest slows down calculation

Why does manually specifying the distance metric to Nearest slow down the calculation so much? This is relevant to my previous question. I've been using ...