Rehsaping Data Table to new format

Question

Matt 2017-4-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/334285-rehsaping-data-table-to-new-format

回答： Matt 2017-4-10

采纳的回答： Peter Perkins

Hi, I have a data table that exists like:

[date] [field] [data]

1/1/2017 A 1

1/2/2017 A 2

1/3/2017 A 3

1/1/2017 B 3

1/2/2017 B 2

1/3/2017 B 1

1/1/2017 C 4

1/2/2017 C 5

1/3/2017 C 6

and i want to reshape the data to be like this:

[Date] [A] [B] [C]

1/1/2017 1 3 4

1/2/2017 2 2 5

1/3/2017 3 1 6

so that each unique value in fields becomes a new field name in the new table.

I saw this conversion done in a tutorial the other day, but cant recall how it was done at all, thanks for any input in advance!

Matt

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Answer 1

Peter Perkins 2017-4-7

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https://ww2.mathworks.cn/matlabcentral/answers/334285-rehsaping-data-table-to-new-format#answer_262256

在 MATLAB Online 中打开

I think you are looking for unstack:

>> t = cell2table( ...
    {'1/1/2017', 'A', 1; ...
     '1/2/2017', 'A', 2; ...
     '1/3/2017', 'A', 3; ...
     '1/1/2017', 'B', 3; ...
     '1/2/2017', 'B', 2; ...
     '1/3/2017', 'B', 1; ...
     '1/1/2017', 'C', 4; ...
     '1/2/2017', 'C', 5; ...
     '1/3/2017', 'C', 6},'VariableNames',{'date' 'field' 'data'});
>> t.date = datetime(t.date,'InputFormat','MM/dd/yyy');
>> t.field = categorical(t.field)
t =
  9×3 table
       date        field    data
    ___________    _____    ____
    01-Jan-2017      A       1  
    02-Jan-2017      A       2  
    03-Jan-2017      A       3  
    01-Jan-2017      B       3  
    02-Jan-2017      B       2  
    03-Jan-2017      B       1  
    01-Jan-2017      C       4  
    02-Jan-2017      C       5  
    03-Jan-2017      C       6  
>> t2 = unstack(t,'data','field')
t2 =
  3×4 table
       date        A    B    C
    ___________    _    _    _
    01-Jan-2017    1    3    4
    02-Jan-2017    2    2    5
    03-Jan-2017    3    1    6

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Answer 2

Steven Lord 2017-4-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/334285-rehsaping-data-table-to-new-format#answer_262255

If your data is stored in a table or timetable, use unstack. The first example on that documentation page is pretty close to the exact scenario you gave, so it should be easy to adapt for your needs.