How to find index and copy data to the another table having same label?

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HCLEE 2022-11-9

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https://ww2.mathworks.cn/matlabcentral/answers/1846693-how-to-find-index-and-copy-data-to-the-another-table-having-same-label

评论： Star Strider 2022-11-9

采纳的回答： Star Strider

test.xlsx

Hi,

There are 'table1' and 'table 2' which have same index labels.

The table 1 has data and I want copy them to the table 2 as shown in below picture.

I'm not sure which code is prefer to me.

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Answer 1

Star Strider 2022-11-9

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I would experiment by vertically concatenatating the two tables and then use sortrows on the result to sort them by the first column. I can’t fiund the appropriate documentation just now, however that would work just like vertically concatenating arrays —

Table3 = [Table1; Table2]

T1 = array2table(randi(9, 5, 4), 'VariableNames',{'1st class','2nd class','mass(kg)','conc(%)'})
T1 = 5×4 table
    1st class    2nd class    mass(kg)    conc(%)
    _________    _________    ________    _______

        5            1           1           6   
        5            9           5           2   
        9            6           5           1   
        3            9           6           6   
        5            5           7           3   
T2 = array2table(randi(9, 5, 4), 'VariableNames',{'1st class','2nd class','mass(kg)','conc(%)'})
T2 = 5×4 table
    1st class    2nd class    mass(kg)    conc(%)
    _________    _________    ________    _______

        4            3           6           3   
        8            2           2           4   
        2            7           4           8   
        8            9           3           8   
        8            3           8           7   
T3 = [T1; T2]
T3 = 10×4 table
    1st class    2nd class    mass(kg)    conc(%)
    _________    _________    ________    _______

        5            1           1           6   
        5            9           5           2   
        9            6           5           1   
        3            9           6           6   
        5            5           7           3   
        4            3           6           3   
        8            2           2           4   
        2            7           4           8   
        8            9           3           8   
        8            3           8           7   
T3 = sortrows(T3,1)
T3 = 10×4 table
    1st class    2nd class    mass(kg)    conc(%)
    _________    _________    ________    _______

        2            7           4           8   
        3            9           6           6   
        4            3           6           3   
        5            1           1           6   
        5            9           5           2   
        5            5           7           3   
        8            2           2           4   
        8            9           3           8   
        8            3           8           7   
        9            6           5           1   

That approach at least works when I test it here.

.

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HCLEE 2022-11-9

The question was not about the sortrows, but the 'data copy' to the same class which already exist in the Table 2 from the Table 1.

I'm not sure, but think that the step for finding and matching the 1st and 2nd class names is needed first. And then copying data of mass and conc. step would be followed.

Star Strider 2022-11-9

The point I make here is that you can vertically concatenate both tables, and that is likely what you want to do. The sortrows call simply sorts the first column to get the desired result (so all the ‘A’ values are at the top, the ‘B’ values next, and so for the rest).

Copying the values from one table to another would mean vertically concatenating the tables and then sorting them. This is not (at least as it appears to me) a join operation, although you can certainly experiment with that if you so desire.

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