`sortregions`

Reorders the regions of a polyshape by a chosen criterion.

Category: Mathematics > Computational Geometry

Syntax

pshape = sortregions(pshape, criterion)

Sorts the regions in ascending order of the criterion.

pshape = sortregions(pshape, criterion, direction)

Sorts in 'ascend' or 'descend' order.

Description

It works like sortboundaries, but treats a region together with its holes as one unit. The order matters for functions that take a region index, such as regions(pshape, I) and area(pshape, I).

Input arguments

criterion: 'area', 'perimeter', 'numsides' or 'centroid'.
direction: 'ascend' (default) or 'descend'.

Output arguments

pshape: The same shape with its regions stored in the new order; each hole stays with its region.

Example

Order two islands by area

P = polyshape([0 1 1 0 NaN 3 5 5 3], [0 0 1 1 NaN 0 0 2 2]);
S = sortregions(P, 'area', 'ascend');
S.Vertices

Output

sortregions