MATLAB: How to define an empty table of unknown size

MATLABtablevariabletype

Hi,

I want to define an empty table to fill in a for loop. The size of the table is defined by another variable. How do I define the "VariableType" variable without knowing how many variables there are? In my case they will all be strings. Example:

T = table('Size', [2, numel(Elements)], 'VariableType',["string","string","string","string","string"]);

In this particular cae, numel(Elements) would be 5. But how do I define the table if I don't know numel(Elements) ?

Best Answer

Elements = 1:5;
n = numel(Elements);
T = table('Size', [2 n], 'VariableTypes', repmat("string", 1, n))

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

You are close, but you are trying to assign a character vector to a double variable (NaN = not a number). You can see that if you run the command summary(mytable).

You also do not need to put the text into a cell if you use the string data type.

See if you can get this code to work for your needs.

myArray = nan(5,2)
mytable = array2table(myArray);
mytable.Properties.VariableNames = {'colA', 'colB'};
mytable2 = convertvars(mytable,"colB",'string');
mytable2.colA(:) = 459;
mytable2.colB(:) = "words"

You say you have a lot of data. If the variables already exist, you could do something like this:

colA = nan(5,1);
colB = strings(5,1);
mytable = table(colA,colB);
mytable.colA(:) = 459; % just a random number, proof-of-concept that it works
mytable.colB(:) = "words" % this throws errors

MATLAB: Subscripted assignment dimension mismatch for table variable

I dont know how to define it from size but there's an other way

T_partialdata = table([1;2;3],[4,4;5,5;6,6],[7;8;9])
sz = [10 3];
varTypes = {'double','double','double'};
T = table('Size', sz, 'VariableTypes', varTypes, 'VariableNames', {'A','B','C'});
T.B = zeros(sz(1),2); % defining the size of variable 
T(1:3,:) = T_partialdata

Best Answer

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

MATLAB: Subscripted assignment dimension mismatch for table variable

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