Grouping Variables using rowfun Function Rearranging Order to Alphabetical

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Jay
Jay 2019-7-24
评论： Jay 2019-7-25
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.

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Walter Roberson
Walter Roberson 2019-7-24
unique() with 'stable' option. Take the third output and use it as the grouping for splitapply()
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Walter Roberson
Walter Roberson 2019-7-24
Stephen's elaboration of what I wrote is correct. You need the third of the three possible outputs from unique() in order to use as the grouping variable for splitapply()
Jay
Jay 2019-7-25
data = readtable('ML_Q_2_2.xlsx', 'ReadVariableNames', false);
data = rmmissing(data); %get rid of empty rows
[~,~,X] = unique(data,'stable')
output = splitapply(@sum,data, X) % Error returned
Error returned for "output":
Group numbers must be a vector of positive integers, and cannot be a sparse vector.
Also, "X" is returning a vector based on the values in the second column and not the key variables of the first column (data):
I.E.
[1 2 3 4 5 1 6 7 8 9 1 10 11 12 13 1 14 15 16 1 17 18 19 1 20 21 22 ].
Not [1 2 3 4 5].
I resolved this by specifying the first column
[~,~,X] = unique(data(:,1),'stable')
I then used the following code to sum the values of the second column to their correlating key variables.
grouped = splitapply(@sum,data(:,2), X)
Thank you for pointing me in the right direction Walter.

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