Find NaN values in cell array that stores changing types of elements over time

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AmelieH 2018-7-21

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https://ww2.mathworks.cn/matlabcentral/answers/411425-find-nan-values-in-cell-array-that-stores-changing-types-of-elements-over-time

评论： dpb 2018-7-22

I have a 1x2 cell array (paths_upd) that stores the output of dijkstra's algorithm for two different cases. A single output(paths_upd{n} is usually also a cell array with vectors stored inside.

These vectors represent paths in a network between nodes (source nodes and target nodes; similar to an adjaceny matrix). Whenever there is no connection between 2 nodes NaN will be returned instead.

An example for paths_upd{n}:

>> paths_upd{1}

ans =

2×4 cell array
    {1×2 double}    {1×3 double}    {1×3 double}    {1×4 double}
    {1×3 double}    {1×2 double}    {1×3 double}    {1×2 double}

I want to identify any target nodes that are entirely disconnected. If in the column of a target node only NaN entries exist, there is no connection to that target node from any of the source nodes.

I have successfully used the following code to identify these target nodes:

f=target_nodes(sum(cell2mat(cellfun(@(x) any(~isnan(x)),paths_upd{1},'UniformOutput',false)),1)==0);

For the case that only one source node and one target node exist and they are disconnected the function will return NaN (double) instead of a cell array. In this case I get the following error message:

Input #2 expected to be a cell array, was double instead.

How do I best proceed to identify the disconnected target nodes for both case?

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dpb 2018-7-21

Show the code that generates the result to be tested; probably the way to solve the problem is to ensure it always returns the same type; perhaps you'll have to special-case it there.

I'd choose to do it at that point rather than make the fixup here, later...

AmelieH 2018-7-21

编辑：dpb 2018-7-21

Available from https://in.mathworks.com/matlabcentral/fileexchange/20025-dijkstra-s-minimum-cost-path-algorithm

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Answer 1

dpb 2018-7-21

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在 MATLAB Online 中打开

I'd still fix it there...the very last thing in the function

function [costs,paths] = dijkstra(AorV,xyCorE,SID,FID,showWaitbar)
  ...

is--

    % Pass the path as an array if only one source/destination were given
    if L == 1 && M == 1
        paths = paths{1};
    end

I'd simply comment that out and all should be well and the outputs will be consistent data types for all conditions thus maintaining symmetry.

I see nothing that would prevent you from doing this that would violate any conditions placed on the code by the author; the submission seems silent on the point.

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AmelieH 2018-7-22

Thanks, this really is the best decision. Makes everything else easy to deal with.

dpb 2018-7-22

Indeed, why the author chose to do that and break symmetry is bad design choice imo...I complain to TMW a lot about their penchant to do similar things in and between related functions! :)

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