Why does table creation produce error "VariableNames property must contain one name for each variable in the table"?

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KAE 2017-1-16

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https://ww2.mathworks.cn/matlabcentral/answers/320659-why-does-table-creation-produce-error-variablenames-property-must-contain-one-name-for-each-variabl

评论： Steven Lord 2024-1-31

Can you please revise the following line of code to eliminate the error "VariableNames property must contain one name for each variable in the table"? I am stumped.

    T = table(rand(30,8), 'VariableNames', ...
      {'var1' 'var2' 'var3' 'var4' 'var5' 'var6' 'var7' 'var8'});

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Answer 1

KAE 2017-1-16

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https://ww2.mathworks.cn/matlabcentral/answers/320659-why-does-table-creation-produce-error-variablenames-property-must-contain-one-name-for-each-variabl#answer_250815

编辑：KAE 2017-1-17

在 MATLAB Online 中打开

Just figured this out: have to use array2table,

   T = array2table(rand(30,8), ...
      'VariableNames', {'var1' 'var2' 'var3' 'var4' 'var5' ...
      'var6' 'var7' 'var8'});

However if you want to assign other properties besides names, you have to do that separately, unlike the table command,

T.Properties.VariableUnits = {'kg' 'm' 'W' 's' 'g' 'kg' 'm' 'W'};

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Emily Jung 2021-9-6

This is so helpful! Thanks for sharing the tip :)

Steven Lord 2024-1-31

在 MATLAB Online 中打开

Another MATLAB oddity to add to the list of annoyances/inconsistencies.

It's not an inconsistency.

When you call table like that, you're asking MATLAB to create a table with one variable, not eight. That one variable happens to contain eight columns. As a smaller example, here's a table with one variable that contains a two-column matrix. Note that the size of T1 is [5 1] not [5 2].

X = randi(10, 5, 2);
T1 = table(X, VariableNames = "Coordinates")
T1 = 5×1 table
    Coordinates
    ___________

      2    5   
      9    8   
      9    2   
      7    7   
      3    8   
size(T1)
ans = 1×2
     5     1

When you use array2table instead, MATLAB creates one variable per column of the input. The size of T2 is [5 2].

T2 = array2table(X, VariableNames = ["X coordinate", "Y coordinate"])
T2 = 5×2 table
    X coordinate    Y coordinate
    ____________    ____________

         2               5      
         9               8      
         9               2      
         7               7      
         3               8      
size(T2)
ans = 1×2
     5     2