Can the attempted addition of a new column to a timetable be intentionally prevented?

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Kevin Johnson 2023-1-7

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评论： Kevin Johnson 2023-1-7

After I build a table using particular variables, my code is sufficently complex that I may inadvertantly add a new variable column to the table, for example by slightly mispelling the name of an already exiting variable there.

Can this be prevented?

Thanks

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the cyclist 2023-1-7

The hard part will likely be the definition of what constitutes "inadvertent" vs. intentional. If you can do that, the MATLAB code is probably straightforward.

Can you upload an example table, and the rule?

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Answer 1

Walter Roberson 2023-1-7

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在 MATLAB Online 中打开

If you are currently using dot assignment to update columns, such as

T.prices = something

then instead write wrapper routines such as

T = new_table_var(T, 'prices', zeros(5,1));
newvalue = T.prices + 1.05;
T = change_table_var(T, 'prices', newvalue);
function T = new_table_var(T, whichvar, initialvalues)
  if ismember(whichvar, T.Properties.VariableNames)
      error('Attempt to re-create existing table variable "%s"', whichvar);
  end
  T.(whichvar) = initialvalues;
end
function T = change_table_var(T, whichvar, newvalue)
  if ~ismember(whichvar, T.Properties.VariableNames)
      error('Attempt to set nonexistent table variable "%s"', whichvar);
  end
  T.(whichvar) = newvalue;
end