Table Find Duplicate Rows (double, char, datetime)

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Dave 2021-10-25

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https://ww2.mathworks.cn/matlabcentral/answers/1571588-table-find-duplicate-rows-double-char-datetime

编辑： the cyclist 2021-10-26

Hello, in table A with 100,000 rows and 40 columns, is there a way to find duplicate rows?

The elements are of the type: double, char, datetime

Thanks

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Dave 2021-10-25

I tried the suggestion in this thread but seems to work only for double

https://www.mathworks.com/matlabcentral/answers/305987-identify-duplicate-rows-in-a-matrix

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Answer 1

the cyclist 2021-10-25

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https://ww2.mathworks.cn/matlabcentral/answers/1571588-table-find-duplicate-rows-double-char-datetime#answer_816388

在 MATLAB Online 中打开

You might need to share some more details about your table, but you should be able to use the unique function.

% Make some pretend data, which is 8 rows with 4 unique ones
tbl = array2table([magic(4); magic(4)]);
% Find the unique rows, along with indices for identifying the duplicates
[uniqueTableRows,indexToUniqueRows,indexBackFromUnique] = unique(tbl);

See the documentation for details on the indices that are reported.

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Dave 2021-10-26

编辑：Dave 2021-10-26

The table has double in some columns, char in some columns, datetime in one column

If I use unique it brings the same number of rows (and I check in excel that some rows are identical)

the cyclist 2021-10-26

编辑：the cyclist 2021-10-26

在 MATLAB Online 中打开

Different data types should not be a problem with this method:

% Make some pretend data of different types
n = [1; 2; 1; 1; 2; 1];
c = {'a';'b';'a';'b';'a';'b'};
t = datetime({'2014-05-26';'2014-08-03';'2014-05-26';'2014-08-03';'2014-05-26';'2014-08-03'},'InputFormat','yyyy-MM-dd');
% Put them in a table
tbl = table(n,c,t)
tbl = 6×3 table
    n      c           t     
    _    _____    ___________

    1    {'a'}    26-May-2014
    2    {'b'}    03-Aug-2014
    1    {'a'}    26-May-2014
    1    {'b'}    03-Aug-2014
    2    {'a'}    26-May-2014
    1    {'b'}    03-Aug-2014
% Find the unique rows, along with indices for identifying the duplicates
[uniqueTableRows,indexToUniqueRows,indexBackFromUnique] = unique(tbl)
uniqueTableRows = 4×3 table
    n      c           t     
    _    _____    ___________

    1    {'a'}    26-May-2014
    1    {'b'}    03-Aug-2014
    2    {'a'}    26-May-2014
    2    {'b'}    03-Aug-2014
indexToUniqueRows = 4×1
     1
     4
     5
     2
indexBackFromUnique = 6×1
     1
     4
     1
     2
     3
     2