Access data from table and assign to variables

Question

Dhananjay Singh 2021-8-27

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回答： Campion Loong 2021-8-30

Hi, I am making a program with excel file already converted to table and now I need to code such that when a user gives an input a certain coloumn is taken and then assign certain variables to some particular blocks in that row.

example:

Vehicle speed fuel

Car 50 2

Bike 20 1

Cycle 5 0

Like user gives input as Bike. then I need to assign variables created like speed and fuel to use in further equations.

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Stephen23 2021-8-27

"...then I need to assign variables created like speed and fuel to use in further equations."

Why not just access the data directly from the table?

Dhananjay Singh 2021-8-27

thank you for answering its clear now

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Answer 1

Ive J 2021-8-27

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编辑：Ive J 2021-8-27

在 MATLAB Online 中打开

This might work

tab = table({'Car'; 'Bike'; 'Cycle'}, [50; 20; 5], [2; 1; 0],...
    'VariableNames', {'Vehicle', 'speed', 'fuel'})
tab = 3×3 table
     Vehicle     speed    fuel
    _________    _____    ____

    {'Car'  }     50       2  
    {'Bike' }     20       1  
    {'Cycle'}      5       0  
filterIn = 'Bike'; %input('what to filter? ', 's');
idx = ismember(tab.Vehicle, filterIn);
if ~any(idx)
    fprintf('oops, not found!\n')
    return
end
dataTable = tab(idx, :);
dataStruct = table2struct(dataTable, 'ToScalar', true);

as table:

disp(dataTable)
    Vehicle     speed    fuel
    ________    _____    ____

    {'Bike'}     20       1  

or struct:

disp(dataStruct)
    Vehicle: {'Bike'}
      speed: 20
       fuel: 1

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Dhananjay Singh 2021-8-27

after getting this is there a way we can assign say x = speed i.e x = 20. x is already defined

Thank you for this.

Ive J 2021-8-27

编辑：Ive J 2021-8-27

在 MATLAB Online 中打开

Yes you can easily assign struct fields to variables, but it's better to use structs as they are, it's much easier and more clear!

x = dataStruct.speed; % or other field names, see fieldnames help

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Answer 2

Campion Loong 2021-8-30

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Picking up from @Ive J's example, but use 'Vehicle' as Row Labels to take advantage of native table indexing:

t = table([50; 20; 5], [2; 1; 0], 'VariableNames', ["speed", "fuel"], 'RowNames', ["Car"; "Bike"; "Cycle"])
t = 3×2 table
             speed    fuel
             _____    ____

    Car       50       2  
    Bike      20       1  
    Cycle      5       0  
t("Bike", ["speed", "fuel"])    % or if you want all variables, t("Bike", :)
ans = 1×2 table
            speed    fuel
            _____    ____

    Bike     20       1  