removeisolatednode.m

function [no, el, fa] = removeisolatednode(node, elem, face)
%
% [no,el,fa]=removeisolatednode(node,elem,face)
%
% remove isolated nodes: nodes that are not included in any element
%
% author: Qianqian Fang, <q.fang at neu.edu>
%
% input:
%     node: list of node coordinates
%     elem: list of elements of the mesh, can be a regular array or a cell array for PLCs
%     face: (optional) list of triangular surface face
%
% output:
%     no: node coordinates after removing the isolated nodes
%     el: element list of the resulting mesh
%     fa: (optional) face list of the resulting mesh
%
% -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
%

oid = 1:size(node, 1);       % old node index
if (~iscell(elem))
    idx = setdiff(oid, elem(:)); % indices to the isolated nodes
else
    el = cell2mat(elem);
    idx = setdiff(oid, el(:)); % indices to the isolated nodes
end
idx = sort(idx);
delta = zeros(size(oid));
delta(idx) = 1;
delta = -cumsum(delta);     % calculate the new node index after removing the isolated nodes
oid = oid + delta;            % map to new index
if (~iscell(elem))
    el = oid(elem);             % element list in the new index
else
    el = cellfun(@(x) oid(x), elem, 'UniformOutput', false);
end
if (nargout >= 3 && nargin >= 3)
    if (~iscell(face))
        fa = oid(face);             % face list in the new index
    else
        fa = cellfun(@(x) oid(x), face, 'UniformOutput', false);
    end
end
no = node;
no(idx, :) = [];             % remove the isolated nodes