combination function using ndgrid
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Hello,
I want to build a function which use ndgrid.
My function is
function [ varargout ] = comb( varargin )
[varargout]=ndgrid(varargin)
varargout=varargout(:);
disp([varargout])
end
My varargout are x1 x2 x3 and varargin are a,b,c where a=[1 2], b=[2 3] and c=[1 4]. Expected results are
1 2 1
2 2 1
1 3 1
2 3 1
1 2 4
2 2 4
1 3 4
2 3 4
but it seems like ndgrid doesn't work. What can i do? In command window works fine but as a function where I can put more varargins something is wrong.
采纳的回答
Guillaume
2016-5-18
function varargout = comb(varargin)
varargout = cell(1, nargout);
[varargout{:}] = ndgrid(varargin{:}; %distribute to varargout
varargout = cellfun(@(m) reshape(m, [], 1), varargout, 'UniformOutput', false); %reshape into columns
end
10 个评论
Nik Sam
2016-5-18
So do you want one output as a matrix, or a variable number of outputs as vectors?
If you just want one output as a matrix, then you misled us with your varargout and the function is simply:
function c = comb(varargin)
c = cell(size(varargin));
[c{:}] = ndgrid(varargin{:};
c = cell2mat(cellfun(@(m) reshape(m, [], 1), c, 'UniformOutput', false)); %reshape into columns and convert to matrix
end
Guillaume
2016-5-18
What you are saying makes no sense. You say you want three outputs (x1, x2, and x3) and then show what looks like a single matrix.
The x1, x2, and x3 returned by my first function are the columns of that matrix. The matrix returned by second function is that matrix.
You can use either form to calculate your F:
%using variable number of outputs:
[x1, x2, x3] = comb(a, b, c); %1st version of comb
F = x1 .* (x2 - x3)
%using single output:
x123 = comb(a, b, c); %2nd version of comb
F = x123(:, 1) .* (x123(:, 2) - x123(:, 3))
Nik Sam
2016-5-18
Guillaume
2016-5-19
I'll say again: "What you are saying makes no sense. You say you want three outputs (x1, x2, and x3) and then show what looks like a single matrix".
You can of course concatenate the 3 outputs for display. Using the varargout form of comb:
[x1, x2, x3] = comb(a, b, c);
[x1, x2, x3] %for display
F = x1 .* (x2 - x3)
T = min(F)
W = max(F)
Nik Sam
2016-5-19
Guillaume
2016-5-19
[varargout{:}]
at the end of the function will do it. This will always display the output whether or not you terminate the call to comb with a semicolon, so I wouldn't recommend it.
There is no way to detect if a function has called with a semicolon or not, so you can't toggle that behaviour.
Nik Sam
2016-5-19
更多回答（2 个）
Walter Roberson
2016-5-18
[varargout{:}] = ndgrid(varargin{:});
3 个评论
Nik Sam
2016-5-18
Walter Roberson
2016-5-18
function [ varargout ] = comb( varargin )
[varargout{1:nargout}] = ndgrid(varargin{:});
end
Nik Sam
2016-5-18
Jos (10584)
2016-5-18
0 个投票
Take a look the content of ALLCOMB, which does exactly what you're after btw...
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