CODEWITHSUNDEEP
arraysmatlabindexingstructcell
MASON CHAN SCOTT
MASON CHAN SCOTT

Reputation: 33

How can I make my index function faster?

So given an struct array, Index with fields, Word, Documents, Locations, it takes a cell array of char arrays and indexes it into Index and also records the DocNums of documents that index appears in. 

function Index = InsertDoc(Index, newDoc, DocNum)
    for i = 1:numel(newDoc) 
        contains = any(strcmpi(newDoc(i),[Index.Word]));
        if any(contains);
            curr = find(strcmpi(newDoc(i),[Index.Word]),true);
            Index(curr).Documents{1} = unique([Index(curr).Documents{1},DocNum]);
            if (numel(Index(curr).Documents{1}) ~= numel(Index(curr).Locations))
                Index(curr).Locations{end+1} = [i];
            else
                Index(curr).Locations{end} = [Index(curr).Locations{end},i];
            end

        else 
            curr = numel(Index) + 1;
            Index(curr).Word = [newDoc(i)];
            Index(curr).Documents = {DocNum};
            Index(curr).Locations = {[i]};
        end
    end
end

For example 

Doc1 = {'Matlab', 'is', 'awesome'};
Doc2 = {'Programming', 'is', 'very', 'very', 'fun'};
Doc3 = {'I', 'love', 'Matlab','very','much};

someIndex = InitializeIndex;
% InitializeIndex just creates struct array with the given fields and empty cell arrays
someIndex = InsertDoc(someIndex, Doc1, 1);
someIndex = InsertDoc(someIndex, Doc2, 2);
someIndex = InsertDoc(someIndex, Doc3, 3);

The result would be for someIndex(1) 

Word: 'Matlab'
Documents: [1 3]
Locations: {[1] [3]}

someIndex(2)

Word: 'is'
Documents: [1 2]
Locations: {[2] [2]}

someIndex(5)

Word: 'very'
Documents: [2 3]
Locations: {[3 4] [4]}

I need to be able to run this with a struct array of 20000 elements with a variety of words, and right now it takes and absurd amount of time to finish indexing. How can I improve this algorithm?

Upvotes: 0

Views: 69

Answers (1)

Lati
Lati

Reputation: 341

Try to allocate memory for your cell array "Index" before your loop starts.

Upvotes: 1

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