How to convert a table containing numbers and booleans to a double array?

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hanspeter 2024-7-5，20:47

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https://ww2.mathworks.cn/matlabcentral/answers/2134881-how-to-convert-a-table-containing-numbers-and-booleans-to-a-double-array

评论： Walter Roberson 2024-7-5，23:19

using table2array I get a string array, but I need an array of numbers where the booleans become 0 or 1 respectivly. double(table2array(arr)) results in NaN for every boolean value

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the cyclist 2024-7-5，21:29

编辑：the cyclist 2024-7-5，21:30

It would be easier for us to suggest a solution if you uploaded a representative sample of your data. You can use the paper clip icon in the INSERT section of the toolbar.

hanspeter 2024-7-5，22:14

example.mat

whoops, I just noticed that the "booleans" weren't actual booleans, but string that were either "TRUE" or "FALSE". I was sure I checked that. With acutal booleans a simple table2array works just fine.

Anyway I attached an example table as the issue still persists. How do I convert this table to an array of doubles?

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Answer 1

Voss 2024-7-5，22:40

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编辑：Voss 2024-7-5，23:00

在 MATLAB Online 中打开

example.mat

T = load('example.mat').data3
T = 1x2 timetable
    time      var1      var2
    _____    _______    ____

    0 sec    "FALSE"    2.52
M = [strcmpi(T.var1,'TRUE') T.var2]
M = 1x2
         0    2.5200
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Voss 2024-7-5，23:10

在 MATLAB Online 中打开

Here's one way to do that:

T = table(["FALSE";"TRUE";"FALSE";"FALSE"],[1.1;2.2;3.3;4.4],["TRUE";"TRUE";"FALSE";"TRUE"])
T = 4x3 table
     Var1      Var2     Var3  
    _______    ____    _______

    "FALSE"    1.1     "TRUE" 
    "TRUE"     2.2     "TRUE" 
    "FALSE"    3.3     "FALSE"
    "FALSE"    4.4     "TRUE" 
[m,n] = size(T);
M = NaN(m,n);
for ii = 1:n
    if isstring(T.(ii))
        M(:,ii) = strcmpi(T.(ii),'TRUE');
    else
        M(:,ii) = T.(ii);
    end
end
M
M = 4x3
         0    1.1000    1.0000
    1.0000    2.2000    1.0000
         0    3.3000         0
         0    4.4000    1.0000
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Walter Roberson 2024-7-5，23:19

在 MATLAB Online 中打开

@hanspeter

One approach would be to use

mask = varfunc(@isnumeric, T, OutputFormat = "uniform");
Output = zeros(height(T), width(T));
Output(:,mask) = T{:,mask};
Output(:,~mask) = varfunc(@(V)strcmpi(V, "TRUE"), InputVariables = ~mask, OutputFormat = "uniform");