Averaging sequential data if values are the same?

Question

yz 2017-8-10

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https://ww2.mathworks.cn/matlabcentral/answers/352300-averaging-sequential-data-if-values-are-the-same

评论： yz 2017-8-11

I want to be able to average the values of an array of n rows and 5 columns, based on the repeated values of a specific column.

I only want to average the values that are next to each other and not all that repeat. Such that:

%Original data:
key_column = [-6 -6 -6 -6 -5 -5 -3 -3 -3 -1 -1 -1 0 0  1 1 2 2 2 3 3 5 5 5 5 6 6 6 6 4 4 4 3 3 3 3 3 3 3 2 2 2 1 1 1 1 0 0 -1 -1 -2 -3 -5 -5 -5 -5 -5 -5 -5 -6 -6 -6];
%Ends up as:
key_column_avg = [-6 -5 -3 -1 -0 1 2 3 5 6 4 3 2 1 0 -1 -2 -3 -5 -6]

I'm running into trouble because the values of the repeated numbers appear at multiple points in the column and I only want the to be averaged if they are "next to each other" on the column. Also, I'm having issues because the number of repeated values isn't the same for each number. Sometimes the value repeats for 10 times, sometimes for 3, sometimes for 7, sometimes for 4.

Is it possible to do this?

Thank you.

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yz 2017-8-10

No, I want to average all columns based on the repeated sequential values of this specific column.

yz 2017-8-10

data_set_example.m

Attached is a sample of my data set. Column 4 is the column of interest for the averaging, but I wish to apply the averaging to all columns (based on the n number of values on column 4)

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Answer 1

Andrei Bobrov 2017-8-10

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https://ww2.mathworks.cn/matlabcentral/answers/352300-averaging-sequential-data-if-values-are-the-same#answer_277542

在 MATLAB Online 中打开

key_column_avg = key_column(diff([0,key_column(:)'],1,2) ~= 0);

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Andrei Bobrov 2017-8-10

编辑：Andrei Bobrov 2017-8-10

在 MATLAB Online 中打开

d = data_example;
g = cumsum(diff([0;d(:,4)]) ~= 0);
out = splitapply(@mean,d,g);

or

d = data_example;
g = cumsum(diff([0;d(:,4)]) ~= 0);
[gg,c] = ndgrid(g,1:size(d,2));
out1 = accumarray([gg(:),c(:)],d(:),[],@mean);

yz 2017-8-11

Thank you so much!

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Answer 2

KL 2017-8-10

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https://ww2.mathworks.cn/matlabcentral/answers/352300-averaging-sequential-data-if-values-are-the-same#answer_277545

在 MATLAB Online 中打开

key_column_avg = key_column(diff([0 key_column])~=0);

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Answer 3

José-Luis 2017-8-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/352300-averaging-sequential-data-if-values-are-the-same#answer_277546

在 MATLAB Online 中打开

key_column = [-6 -6 -6 -6 -5 -5 -3 -3 -3 -1 -1 -1 0 0  1 1 2 2 2 3 3 5 5 5 5 6 6 6 6 4 4 4 3 3 3 3 3 3 3 2 2 2 1 1 1 1 0 0 -1 -1 -2 -3 -5 -5 -5 -5 -5 -5 -5 -6 -6 -6];
result = [key_column(diff(key_column) > 0), key_column(end) ]