Search through every vector in cell array for the vector that contains a certain value

Question

han 2020-4-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/517323-search-through-every-vector-in-cell-array-for-the-vector-that-contains-a-certain-value

评论： han 2020-4-12

Hiya,

I have the below code, which instead of searching through every vector in the cell array for a vector that contains the number 1, it goes to the last vector in the cell array and returns false.

my cell array is called nodey and contains in position {1,1} - [1,2] and in position {1,2} - [3,4]

for i = 1:length(nodey)
ismember(nodey{i},1);
end

I need it so that it returns true for the first vector, and then i can return nodey{i} and it'll be [1,2] since the value is in the first vector

Thanks!

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Answer 1

per isakson 2020-4-12

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https://ww2.mathworks.cn/matlabcentral/answers/517323-search-through-every-vector-in-cell-array-for-the-vector-that-contains-a-certain-value#answer_425536

在 MATLAB Online 中打开

Try this

%%
nodey = {[1,2],[3,4]};
%%
has_one = false(1,length(nodey));
for ii = 1:length(nodey)
    has_one(ii) = ismember( 1, nodey{ii} );
end
%%
has_one
nodey{ has_one }
%%
ix_one = find( has_one )
nodey{ ix_one }

it displays

has_one =
  1×2 logical array
   1   0
ans =
     1     2
ix_one =
     1
ans =
     1     2

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han 2020-4-12

This worked perfectly!! Thank you so much

Have a nice day

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Answer 2

dpb 2020-4-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/517323-search-through-every-vector-in-cell-array-for-the-vector-that-contains-a-certain-value#answer_425539

在 MATLAB Online 中打开

Your code above doesn't save the result going thru the loop so you only show the final result at the end---

ix=cellfun(@(v) ismember(1,v),nodey,'UniformOutput',1);
>> ix
ix =
  2×1 logical array
   1
   0
>>

Better form for coding would be to put the value to search for in a variable so can only change the variable to look for alternate values...

VFIND=1;
ix=cellfun(@(v) ismember(VFIND,v),nodey,'UniformOutput',1);

BTW: NB the order of arguments to ismember to have the first value the one-element searched-for value so returns a single result instead of a logical vector of numel(nodey) as the first output.