ISLANDS

Finds all "islands" which are 4-connected components in a matrix.
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Updated 23 Sep 2008

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ISLANDS finds all "islands" which are 4-connected components in a matrix. The function will return three output arguments, including the largest connected island in the input matrix. See the detailed help for all descriptions.

Inspired by a recent puzzler posted here:
http://blogs.mathworks.com/pick/2008/08/18/puzzler-find-largest-connected-island/
and by the submission from Tim Davis.

Also included is a MEX-File version which runs faster than the M-File version.

Tested on 2007a and 2007b.

Please email me about bugs and other concerns. Thanks.

Cite As

Matt Fig (2026). ISLANDS (https://www.mathworks.com/matlabcentral/fileexchange/21376-islands), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2007b
Compatible with any release
Platform Compatibility
Windows macOS Linux
Version Published Release Notes
1.0.0.0

Now 3 times faster for a large binary matrix.