# nearestsegment: Find Line Segment Nearest to Each Point In spatstat: Spatial Point Pattern Analysis, Model-Fitting, Simulation, Tests

## Description

Given a point pattern and a line segment pattern, this function finds the nearest line segment for each point.

## Usage

 `1` ```nearestsegment(X, Y) ```

## Arguments

 `X` A point pattern (object of class `"ppp"`). `Y` A line segment pattern (object of class `"psp"`).

## Details

The distance between a point `x` and a straight line segment `y` is defined to be the shortest Euclidean distance between `x` and any location on `y`. This algorithm first calculates the distance from each point of `X` to each segment of `Y`. Then it determines, for each point `x` in `X`, which segment of `Y` is closest. The index of this segment is returned.

## Value

Integer vector `v` (of length equal to the number of points in `X`) identifying the nearest segment to each point. If `v[i] = j`, then `Y[j]` is the line segment lying closest to `X[i]`.

## Author(s)

and \rolf

`project2segment` to project each point of `X` to a point lying on one of the line segments.

Use `distmap.psp` to identify the nearest line segment for each pixel in a grid.

## Examples

 ```1 2 3 4 5 6 7``` ``` X <- runifpoint(3) Y <- as.psp(matrix(runif(20), 5, 4), window=owin()) v <- nearestsegment(X,Y) plot(Y) plot(X, add=TRUE) plot(X[1], add=TRUE, col="red") plot(Y[v[1]], add=TRUE, lwd=2, col="red") ```

### Example output

```Loading required package: nlme