getnumnodes.m

function numnodes = getnumnodes(expr)
%GETNUMNODES Returns the number of nodes in an encoded tree expression or the total node count for a cell array of expressions.
%
%   NUMNODES = GETNUMNODES(EXPR) finds the number of nodes in the GP
%   expression EXPR or cell array of expressions EXPR.
%
%   Copyright (c) 2009-2015 Dominic Searson 
%
%   GPTIPS 2
%
%   See also GETDEPTH, GETCOMPLEXITY

if isa(expr,'char')
 
    numnodes = getnn(expr);
    return;
    
elseif iscell(expr)
    
    numexpr = numel(expr);
    
    if numexpr < 1
        error('Cell array must contain at least one valid symbolic expression');
    else
        numnodes = 0;
        for i=1:numexpr
            numnodes = numnodes + getnn(expr{i});
        end
    end
else
    error('Illegal argument');
end

function numnodes=getnn(expr)
%GETNN get numnodes from a single symbolic string

%number of nodes = number of open brackets +number of inputs +number of
%constants
open_br = strfind(expr,'(');
open_sq_br = strfind(expr,'[');
inps = strfind(expr,'x');

num_open = numel(open_br);
num_const = numel(open_sq_br);
num_inps = numel(inps);

numnodes = num_open + num_const + num_inps;