Problem with size of a 0-by-1 empty matrix.

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sam kamiab
sam kamiab 2019-8-1
回答： Steven Lord 2019-8-1
hi dear friends. For computing the jaccard similarity index of a graph's nodes I need to compute a pairwise intersection among their neighborhood matrix and find the number of common neighbors. for example (2, [1,4], [], 2) are neighbors of nodes 1 to 4 and node 3 is alone. The problem is that when I compute the intersection, the size of results for the alone node is [1x0 double] or [0x1 double] like this:
(Int)
[ 2] [1x0 double] [1x0 double] [ 2]
[1x0 double] [1x2 double] [0x1 double] [1x0 double]
[1x0 double] [0x1 double] [0x1 double] [1x0 double]
[ 2] [1x0 double] [1x0 double] [ 2]
and the size of [0x1 double] vector will be computed as 1 while the correct answer is 0 like this!
the size matrix:
1 0 0 1
0 2 1 0
0 1 1 0
1 0 0 1
I have the same problem with union, how can I fix this problem??
related part of my code is this:
[ii, jj] = ndgrid(1:Size) %Size=number of nodes
H=NeighborsS(L1,:); %%% I have a multiplex network and L1 is the layernumber
result= arrayfun(@(n) intersect(H{ii(n)},H{jj(n)}), 1:Size^2, 'uni', 0);
Int(:,:,L1) = reshape(result,Size,Size);
IntNum=cellfun('size',Inti,2);

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采纳的回答

Walter Roberson
Walter Roberson 2019-8-1
empty = cellfun(@isempty, result);
result(empty) = {zeros(0,0)}; %same size of emptiness for each empty result
Int(:,:,L1) = reshape(result,Size,Size);
IntNum = cellfun('size',Inti,2);

更多回答（1 个）

Steven Lord
Steven Lord 2019-8-1
You don't actually care about the size of the neighbors vector, you care about the number of neighbors. Use @numel instead of 'size' in your cellfun call.

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