Count the adjacent same elements in a vector
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Hello! Assume we have a vector of A=[1 1 1 2 2 3 3 3 3 3 1 1]. A has three 1, two 2, five 3 and two 1.
I need to create a vector, such as B=[3 2 5 2] and their corresponding value C=[1 2 3 1].
Maybe i should use a struct, not sure. Glad for some help :/
thx.
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採用された回答
Matt J
2019 年 7 月 1 日
編集済み: Matt J
2019 年 7 月 1 日
L=cumsum([1, diff(A)~=0]);
B=splitapply(@sum,ones(size(A)),L)
C=splitapply(@min,A,L)
2 件のコメント
Jos (10584)
2019 年 7 月 1 日
Nice use of splitapply. Here is a simpler version of run-length encoding:
A=[1 1 1 2 2 3 3 3 3 3 1 1]
x = find([true diff(A)~=0])
B = diff([x numel(A)+1]) % run-lengths
C = A(x) % elements
その他の回答 (1 件)
Jos (10584)
2019 年 7 月 1 日
This is call run-length encoding, for which you can find excellent function on the File exchange. For instance, [shameless self promotion ;-) ], this one: https://uk.mathworks.com/matlabcentral/fileexchange/56131-runindex
A = [1 1 1 2 2 3 3 3 3 3 1 1]
[~, RLE] = runindex(A)
B = RLE(:,3)
C = RLE(:,1)
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