MATLAB: Displaying a different name on columns and rows than the official row or column name

column namesrow namestable

Hi,

I had a question more on the displaying of tables than anything else. I am creating a table with array2table where each column and row has a unique name to identify it. However, when I display the table, I would like for the display to give different names for the column and row names than the official designation. The root of the problem is that I would like to create a table with column and row names which repeat. I understand that the table environment does not allow that so I am creating the table with unique row and column names, but I was wondering if it was possible to change the names that are displayed. Thank you in advance…

Best Answer

No, they display as they truly are. However you can make your own function to take a table and print it out to the command window using fprintf() in exactly the format that you want.

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MATLAB: Table with a few identical column names

Grouping the rows is trivially achieved with varfun in just one line:

newT = varfun(@mean, T, 'GroupingVariables', 1)

The tricky bit is indeed the grouping of the columns as it's not something that's really supported by tables. Probably the easiest way is to use a custom function with rowfun. This can do the row grouping at the same time. Something like:

function varargout = groupingfunction(columngroups, columns)
  %this function to be used with rowfun with the option 'SeparateInputs', false
  %columngroup: row vector of integers from 1:n indicating how to group the column together (all 1 columns together, all 2 columns together, etc.)
  %columns contains the content of the columns of the table
  columngroups = repmat(columngroups, size(columns, 1), 1);  %replicate grouping for each row
  varargout = num2cell(accumarray(columngroups(:), columns(:), [], @mean));
end

You can then use that with rowfun:

columgroups = [1 1 1 2 2 3 3 3 4 4 4 4 5 6 6 6];  %generate that however you want. Indicates how to group the columns together, ignoring the first column
columnames = {'a', 'b', 'c', 'd', 'e', 'f'};  %as many as there are unique values in columngroups
newT = rowfun(@(cols) groupingfunction(columngroups, cols), T, 'GroupingVariables', 1,'SeparateInputs', false, 'NumOutputs', numel(unique(columngroups)), 'OutputVariableNames', columnnames);

A possible way of generating columngroups and columnnames, assuming they're all named prefix_number

prefixes = regexp(T.Properties.VariableNames(2:end), '.*?(?=(_\d+)?$)', 'match', 'once');
[columnnames, ~, columngroups] = unique(prefixes);

edit, now that you've posted some demo data: The above works without issue on your demo data, as long as you transpose the columngroups vector returned by unique:

T = readtable('test.csv');
prefixes = regexp(T.Properties.VariableNames(2:end), '.*?(?=(_\d+)?$)', 'match', 'once');
[columnnames, ~, columngroups] = unique(prefixes);
newT = rowfun(@(cols) groupingfunction(columngroups.', cols), T, 'GroupingVariables', 1,'SeparateInputs', false, 'NumOutputs', numel(unique(columngroups)), 'OutputVariableNames', columnnames);

MATLAB: Spaces between columns, or, table format. How to assemble the table

Yor can use the following command to create a table with m rows and n columns.

t = cell2table(cell(m, n));

You can specify the name of rows and columns of the table using t.Properties.RowNames and t.Properties.VariableNames respectively. For doing what you want, you can do it like this,

for i=1:length(q.Properties.VariableNames)
  q.Properties.VariableNames{i} = strcat('Column ', num2str(i));
end

It will name all columns as Column 1, column 2, ...., Column n.

Best Answer

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MATLAB: Table with a few identical column names

MATLAB: Spaces between columns, or, table format. How to assemble the table

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