Use For Loop to obtains variable name and value from Table

Hi,

I am having trouble automatically creating varaibales from the below table? at the moment doing this by coding each individual column

Any help much appreciated

[Stephen23]

"I am having trouble automatically creating varaibales from the below table? at the moment doing this by coding each individual column"

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

What specifically is preventing you from simply accessing the data in the table?

[Adrian]

The Variable names in the table are generated by another program. It is easier for me to create the individual variables and then post process

[Dyuman Joshi]

You can get the variable names from the table and use them to access the data

names = TableName.Properties.VariableNames

[dpb]

Are the names consistent or do they change all over the place from one file to another? If they always relate to a given property but may just have a different trailing subscript such as the example file but are the same variables as far as processing given the initial name string, I often will do a name substitution to a set of convenient predefined names that are succinct but meaningful for coding. The substitution can be done with string pattern matching to ensure positions aren't moved around. Simply change the Properties.VariableNames cell array as @Dyuman Joshi notes above or use the renamevars function.

Doing it this way means you can code the application with a convenient set of variables and not worry about finding stuff dynamically at all. It can be done that way, but why make things more complicated if simpler can work?

Answer 1

[Arun]

Hi Adrian,

I understand that you want to obtain variable names and data from a table created with automatically created variable names.

This can be done using the table properties or using the “renamevars” function. Here is a code snippet that might be useful:

%creating a sample table 
% you can use dataTable = readtable('yourFile.csv','TextType','string') 
% Define the number of rows and columns 
numRows = 5; 
numCols = 4; 
% Generate random values for the table 
tableData = rand(numRows, numCols); 
% Create a table with column names 
columnNames = {'Column1', 'Column2', 'Column3', 'Column4'}; 
dataTable = array2table(tableData, 'VariableNames', columnNames);

%solution to the issue: 
%using table properties: 
names = dataTable.Properties.VariableNames; 
disp(dataTable.(names{1})); 

    0.9053
    0.4372
    0.1485
    0.6844
    0.7502

%Solution 2: 
%Using renamevars function  
allVars = 1:width(dataTable); 
newNames = append("Reading",string(allVars)); 
dataTable = renamevars(dataTable,allVars,newNames); 
disp(dataTable); 

    Reading1    Reading2    Reading3    Reading4
    ________    ________    ________    ________

    0.90528      0.94104    0.29029      0.58789
    0.43721      0.95657    0.34875      0.86429
    0.14846       0.6348    0.55673      0.29821
    0.68438     0.054584    0.77649     0.068242
    0.75015     0.041656    0.32132      0.63615

disp(dataTable.Reading1); % here we can see that, data is accessed using variables defined by us. 

    0.9053
    0.4372
    0.1485
    0.6844
    0.7502

For more information regarding "renamevars" function please refer the shared MATLAB Documentation link:

https://www.mathworks.com/help/matlab/ref/table.renamevars.html

I hope this helps.