MATLAB: Grouping Variables using rowfun Function Rearranging Order to Alphabetical

MATLAB and Simulink Student Suitename ordering using rowfun for grouping variables

How does one keep the original sequencing of variables used for matching in the rowfun?

% Guillaume's Code from Prior Question
data = readtable('ML_Q_3.xlsx', 'ReadVariableNames', false);
%optionally, give better name to the variables of the table
%data.Properties.VariableNames = {'???', '????'}
data = rmmissing(data);  %get rid of empty rows
sorted = rowfun(@(v) {v}, data, 'GroupingVariables', 1);  %group column 2 by column 1

The resulting sorted names are in alphabetical order (col 1) ['A','B','F','R','X'] .

Where I require it to be per the original ['B','F','R','X','A'] .

I can not find anything in the documentation rowfun how to specify to keep the original order.

Best Answer

unique() with 'stable' option. Take the third output and use it as the grouping for splitapply()

Related Solutions

MATLAB: Sort Through Cell And Put Corresponding Values In Their Respective Rows

This is how I'd do it:

data = readtable('ML_Q_1.xlsx', 'ReadVariableNames', false);
%optionally, give better name to the variables of the table
%data.Properties.VariableNames = {'???', '????'}
data = rmmissing(data);  %get rid of empty rows
sorted = rowfun(@(v) {v}, data, 'GroupingVariables', 1);  %group column 2 by column 1

You can keep the result as a table, or if you really want a cell array:

csorted = sorted{:, [1, 3]}'  %a 2xG cell array. csorted{1, :} is the header, csorted2, :} is the grouped data

MATLAB: Save in a string the values obtained after varfun and grouping

If you want to create a new table with two new variables, one for the number of unique countries and one for the list of unique countries then a) you have to use rowfun instead of varfun, and b) you can't use an anonymous function (since you need a function with 2 outputs) but a normal m function:

function [count, list] = uniquecountries(countries)
   %inputs: 
   %    countries: a list of countries (categorical)
   %    count: the number of unique countries (double)
   %    list: the list of unique countries, joined by a ', ' (scalar cell array of a char vector)
   %Note: list is returned as a scalar cell array instead of a char vector so that rowfun can concatenate the output of uniquecountries
   validateattributes(countries, {'categorical'}, {});
   list = unique(countries);
   count = numel(list);
   list = {strjoin(cellstr(list), ', ')};
end

Then:

sections = rowfun(@uniquecountries, fullTable, ...
                  'GroupingVariables', {'ID1','Date'}, ...
                  'InputVariables', 'Country', ...
                  'NumOutputs', 2, ...
                  'OutputVariableNames', {'Country_count', 'Country_list'})

Alternatively, if you don't want a separate m function, you can have two calls to rowfun or varfun to create two tables that you then join. It will be much slower however:

sectionscount = rowfun(@(v) numel(unique(v)), fullTable, ...
                       'GroupingVariables', {'ID1','Date'}, ...
                       'InputVariables', 'Country', ...
                       'OutputVariableNames', 'Country_count');
sectionslist = rowfun(@(v) {strjoin(cellstr(unique(v)), ', ')}, fullTable, ...
                       'GroupingVariables', {'ID1','Date'}, ...
                       'InputVariables', 'Country', ...
                       'OutputVariableNames', 'Country_list');
sections = join(sectionscount, sectionslist)

Best Answer

Related Solutions

MATLAB: Sort Through Cell And Put Corresponding Values In Their Respective Rows

MATLAB: Save in a string the values obtained after varfun and grouping

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