How to organize a new matrix like matrix B ?

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Pradya Panyainkaew 2018-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/377957-how-to-organize-a-new-matrix-like-matrix-b

评论： Pradya Panyainkaew 2018-1-20

If I have matrix A that contains 4 columns. like this

A = [7210 01/12/2016 00:15:00 0 0.5502;
01/12/2016 00:15:00 2 0.4903;
01/12/2016 00:30:00 0 0.5487;
01/12/2016 00:30:00 2 0.4914 ]

First column is a customer id and second column contains date time data.

I try to construct output matrix B to get the result follow this example

B = [7210 01/12/2016 00:15:00 0.5502 0.4903;
     7210 01/12/2016 00:30:00 0.5487 0.4914]

How can create program to get a result like matrix B ?

Thanks in advance.

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Answer 1

Matt J 2018-1-19

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编辑：Matt J 2018-1-19

在 MATLAB Online 中打开

B=A([2,4],:)

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Pradya Panyainkaew 2018-1-19

Sorry Matt J .

I think it is my fault to explain my point deeply. The last 2 columns of result (Matrix B) show the value of flag "0" and flag "2" (column 3 of A) in each interval. However, your code create only a value of flag "2". How can I modify it to get my result ?

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Answer 2

Akira Agata 2018-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/377957-how-to-organize-a-new-matrix-like-matrix-b#answer_300957

在 MATLAB Online 中打开

Assuming your data A is stored in table format, I believe one possible solution would be like this.

% Your data stored in table format
ID = [7210; 7210; 7210; 7210];
Time = [...
  datetime('01/12/2016 00:15:00','InputFormat','dd/MM/yyyy HH:mm:ss');...
  datetime('01/12/2016 00:15:00','InputFormat','dd/MM/yyyy HH:mm:ss');...
  datetime('01/12/2016 00:30:00','InputFormat','dd/MM/yyyy HH:mm:ss');...
  datetime('01/12/2016 00:30:00','InputFormat','dd/MM/yyyy HH:mm:ss')];
Flag = [0;2;0;2];
Value = [0.5502;0.4903;0.5487;0.4914];
A = table(ID,Time,Flag,Value);
% Create the result B
A1 = A(A.Flag == 0,{'ID','Time','Value'});
A2 = A(A.Flag == 2,{'ID','Time','Value'});
B = innerjoin(A1,A2,'Keys',{'ID','Time'});