For repeating values in a column calculate the corresponding adjacent columns

Question

Gabi 2022-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/1663424-for-repeating-values-in-a-column-calculate-the-corresponding-adjacent-columns

编辑： Gabi 2022-3-7

采纳的回答： Arif Hoq

Hi,

I have a table T with 3 columns to make it simple:

There there is a repeat value in column 1 I would like to calculate the max of the values in column 2, min of the values in column 3 for all corresponding values of col 1 (where the same value was found) and regenerate the table without the repeat values in col 1 and the results as calculated previosly for cols 2 and 3. The number of reps in col 1 can be >2:

Thanks.

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Answer 1

Arif Hoq 2022-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/1663424-for-repeating-values-in-a-column-calculate-the-corresponding-adjacent-columns#answer_909574

编辑：Arif Hoq 2022-3-4

在 MATLAB Online 中打开

A=[1 233 456;2 3434 565; 3 4545 2323; 4 4595 595; 4 121 343; 5 1212 4145]; % assume A is table
B=diff(A(:,1));
[idx]=find(B==0);
A(idx,:)=[]  % delete the row with same value
A = 5×3
           1         233         456
           2        3434         565
           3        4545        2323
           4         121         343
           5        1212        4145

or

A1=[1 233 456;2 3434 565; 3 4545 2323; 4 4595 595; 4 121 343; 5 1212 4145]; % assume A is table
[C,ia,ic]=unique(A1(:,1),'rows','stable');
output=A1(ia,:)
output = 5×3
           1         233         456
           2        3434         565
           3        4545        2323
           4        4595         595
           5        1212        4145

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Gabi 2022-3-4

sample.mat

Table attached Arif. Thanks.

Gabi 2022-3-7

编辑：Gabi 2022-3-7

在 MATLAB Online 中打开

I eneded up using a variation of your code Arif, does the job, in essence I had to order the columns based on the requirements before extracting:

A=table2array(T);
B=sortrows(A,[1 2 4],{'ascend' 'descend' 'ascend'})
[C,ia,ic]=unique(B(:,1),'rows','first')
D=B(ia,:)
E=array2table(D);

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Answer 2

Davide Masiello 2022-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/1663424-for-repeating-values-in-a-column-calculate-the-corresponding-adjacent-columns#answer_909584

编辑：Davide Masiello 2022-3-4

在 MATLAB Online 中打开

I have expanded it for cases where there are multiple repeated values.

clear,clc
A  = [[(1:6)';(6:10)';(10:14)';(14:20)'],rand(23,1),rand(23,1)]
l0 = find(~diff(A(:,1)));
for i = 1:length(l0)
    A(l0(i),2) = max(A(l0(i),2),A(l0(i)+1,2));
    A(l0(i),3) = min(A(l0(i),3),A(l0(i)+1,3));
end
A(l0+1,:) = []

The result you get from this code is

% Before code
A =
            1      0.74618     0.080281
            2      0.11749      0.36047
            3      0.50902      0.82891
            4      0.16883      0.21461
            5      0.83111      0.79104
            6      0.92801      0.65469
            6      0.16948     0.026146
            7      0.88374      0.78578
            8      0.38786      0.92256
            9      0.38257      0.49231
           10      0.27145      0.83401
           10      0.86788      0.13135
           11       0.7415      0.75978
           12      0.44787      0.92574
           13      0.70964      0.83271
           14      0.94433       0.2594
           14      0.17412      0.21302
           15       0.2446      0.52231
           16      0.64093      0.39736
           17      0.80861      0.47911
           18      0.85337       0.9939
           19      0.39812      0.60448
           20      0.11549      0.94491
% After code
A =
            1      0.74618     0.080281
            2      0.11749      0.36047
            3      0.50902      0.82891
            4      0.16883      0.21461
            5      0.83111      0.79104
            6      0.92801     0.026146
            7      0.88374      0.78578
            8      0.38786      0.92256
            9      0.38257      0.49231
           10      0.86788      0.13135
           11       0.7415      0.75978
           12      0.44787      0.92574
           13      0.70964      0.83271
           14      0.94433      0.21302
           15       0.2446      0.52231
           16      0.64093      0.39736
           17      0.80861      0.47911
           18      0.85337       0.9939
           19      0.39812      0.60448
           20      0.11549      0.94491

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Davide Masiello 2022-3-4

在 MATLAB Online 中打开

In the file you gave T is a structure with one field (also named T, which is a table).

At the beginning of your code, write

A=table2array(T.T);

then the rest of the code will work fine.

Gabi 2022-3-4

编辑：Gabi 2022-3-4

Just noticed that this works if there are only 2 same values in column 1, if there are 3 or more it doesn't unfortunately. In other words, the number of repetions in col 1 can vary and it's not max 2.

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