Convert multiple strings in a table to numbers

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YaaW 2023-1-12

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https://ww2.mathworks.cn/matlabcentral/answers/1892930-convert-multiple-strings-in-a-table-to-numbers

评论： YaaW 2023-1-12

I'm trying to convert multiple strings in a table to numbers, but I keep on getting an error (either 'NaN' as an answer, or "Right hand side of an assignment into a table must be another table or a cell array").

It's a table where columns 13:68 contain either a "number" or "" (empty cell), and I want the string numbers to be converted to a number, and the empty cells to a NaN.

It works if I try this for one column only, using:

Table.X = str2double(Table.X);

But I have to do this for 56 columns and there must be a way to do it quicker than for each of them separately, however trying:

Table.(: ,X:YY) = str2double(Table.(: ,X:YY));

doesn't seem to work, as it returns an error, and changing the () to {} returns a NaN.

Anybody that knows how I can easily change string to double for multiple columns in a table?

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Answer 1

Stephen23 2023-1-12

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https://ww2.mathworks.cn/matlabcentral/answers/1892930-convert-multiple-strings-in-a-table-to-numbers#answer_1147215

在 MATLAB Online 中打开

T = cell2table({"cat","1.2","","3.4";"in","4.5","6","7";"hat","","89",""})
T = 3×4 table
    Var1     Var2     Var3    Var4 
    _____    _____    ____    _____

    "cat"    "1.2"    ""      "3.4"
    "in"     "4.5"    "6"     "7"  
    "hat"    ""       "89"    ""   
T = convertvars(T,2:4,'double')
T = 3×4 table
    Var1     Var2    Var3    Var4
    _____    ____    ____    ____

    "cat"    1.2     NaN     3.4 
    "in"     4.5       6       7 
    "hat"    NaN      89     NaN 