Cody Problem 38. Return a list sorted by number of occurrences

Question

Hidd_1 2021-4-5

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/793247-cody-problem-38-return-a-list-sorted-by-number-of-occurrences

编辑： Rik 2023-4-26

I found difficulties with the Problem 38 on Cody here is my solution:

function y = popularity(x)
[a,b]=size(x);
s=ones(a,b);
for i=1:b
    for j=1:b
        if i~=j
            if x(i)==x(j)
                s(i) = s(i) +1;
            end
        end
    end
end
[A,o]= sort(s,'descend');
 for k =1:b
     L(k)=x((o(k)));
 end
y= unique(L,'stable');
end

Unfortunately it doesn't work for the second case, can anyone help me with that!

Thanks in advance.

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Answer 1

David Hill 2021-4-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/793247-cody-problem-38-return-a-list-sorted-by-number-of-occurrences#answer_667572

编辑：David Hill 2021-4-5

Take a look at the functions, histcounts(), sort(), and unique(). By combining these functions you can answer the problem in a few lines without any loops.

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Hidd_1 2021-4-5

编辑：Hidd_1 2021-4-5

It worked Thank you!

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Answer 2

Abhinav 2023-4-26

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/793247-cody-problem-38-return-a-list-sorted-by-number-of-occurrences#answer_1223389

编辑：Rik 2023-4-26

在 MATLAB Online 中打开

function output_array = popularity(input_array)
%% First make unique array
unique_input_array = unique(input_array);
%% Create occurences - keys pair array
table_occurence = zeros(length(unique_input_array),2);
table_occurence(:,2) = unique_input_array';
for i = 1:length(unique_input_array)
    occurrence = numel(find(input_array == unique_input_array(i)));
    table_occurence(i,1) = occurrence;
end
%% Sort by occurences in descending order
sorted_table = sortrows(table_occurence,'descend');
occurences = sorted_table(:,1);
keys = sorted_table(:,2);
%% Find keys that have same occurences and store sorted keys in new array
occurences_total = unique(occurences,'stable');
output_array = [];
for j = 1:length(occurences_total)
    [row,~] = find(occurences == occurences_total(j));
    aa = sort(keys(row));
    output_array = [output_array, [aa']];
end
end