isShapeMultipart

Determine if line or polygon has multiple parts

Syntax

tf = isShapeMultipart(x,y)

Description

tf = isShapeMultipart(x,y) returns 1 (true) when the specified line or polygon has multiple parts that are separated by NaN values. A line with multiple parts has multiple line segments. A polygon with multiple parts has inner rings or nonintersecting regions. If the specified line or polygon consists of a single part, the function returns a logical 0 (false).

Examples

Determine if Line Has Multiple Parts

Specify the latitude and longitude coordinates of a line. Verify that the line does not contain multiple parts.

lat1 = [65 62 53 66];
lon1 = [4 59 121 98];
tf1 = isShapeMultipart(lat1,lon1) 

tf1 = logical
   0

Specify the latitude and longitude coordinates of a line with multiple parts. Separate the parts using NaN values. Verify that the line contains multiple parts.

lat2 = [55 34 18 NaN 14 19 42 26];
lon2 = [78 56 63 NaN 83 106 104 126];
tf2 = isShapeMultipart(lat2,lon2)

tf2 = logical
   1

Determine if Polygon Has Multiple Parts

Read a shapefile containing hydrographic data into the workspace as a structure array. The shapefile represents the data using polygons in planar coordinates.

hydro = shaperead("concord_hydro_area.shp");

Extract a polygon that represents a pond.

pond = hydro(14);

Extract the xy-coordinates from the polygon. Then, determine if the polygon has multiple parts.

x = pond.X;
y = pond.Y;
tf = isShapeMultipart(pond.X,pond.Y)

tf = logical
   1

The result indicates that the polygon has multiple parts. Verify the result by displaying the polygon on a map. Note that the polygon has multiple holes.

mapshow(pond)

Input Arguments

x — First coordinate

numeric vector

First coordinate, specified as a numeric vector. This argument typically specifies x-coordinates or latitude coordinates.

The sizes of x and y must match. The NaN values in x must correspond to the NaN values in y.

y — Second coordinate

numeric vector

Second coordinate, specified as a numeric vector. This argument typically specifies y-coordinates or longitude coordinates.

The sizes of x and y must match. The NaN values in x must correspond to the NaN values in y.

Output Arguments

tf — Indicator for shape with multiple parts

1 | 0

Indicator for a shape with multiple parts, returned as one of these values.

• A 1 of data type logical indicates that the line or polygon has multiple parts.

• A 0 of data type logical indicates that the line or polygon does not have multiple parts.

Version History

Introduced in R2006a