find the mean for each category and summarize it

Hello,

i have a table which consists of the following data

Category value1 value2

1 20 33

3 23 43

2 50 32

4 13 32

4 30 15

3 33 23

1 60 12

2 24 43

i want to find the modulus mean value for each unique category and summarize them, e.g.

Category value1 value2

1 23.54 15.33

2 35.44 42.55

3 29.33 33.32

4 44.34 23.44

can anyone help me with this?

[Mohammad Aljarrah]

they are in numeric array

[the cyclist]

Sorry I deleted my question that you answered here! I decided to just illustrate solutions for both a numeric array and a table.

[Star Strider]

@Mohammad Aljarrah — How do you calculate those results?

The mean of category 1 for example are 40 and 22.5 for ‘value1’ and ‘value2’ respectively. How do you get 23.54 and 15.33?

Answer 1

[the cyclist]

For a numeric array, you can use the accumarray function to do this. That function is a bit tricky to learn the power of, and is also not really set up for operating on a matrix of data. However, Sean de Wolski provided a nice solution here, which I borrow below.

For a table, it is simpler. You can use grouping variables in the varfun function.

I illustrate both below.

M = [1 20 33
     3 23 43
     2 50 32
     4 13 32
     4 30 15
     3 33 23
     1 60 12
     2 24 43];

% On the original matrix
[~,~,c] = unique(M(:,1));
data = M(:,[2 3]);

sz = size(data);

meanByCategoryForMatrix = accumarray([repmat(c,sz(2),1), repelem((1:sz(2))',sz(1),1)],data(:),[],@mean)

% Or put them in a table first
Category = M(:,1);
value1 = M(:,2);
value2 = M(:,3);

tbl = table(Category,value1,value2);

meanByCategoryForTable = varfun(@mean,tbl,'GroupingVariables','Category','InputVariables',{'value1','value2'})

[Mohammad Aljarrah]

thank you very much, that worked perfectly

Answer 2

[Robert U]

Hi Mohammad Aljarrah,

the function that calculates the desired values can be exchanged according to your needs. I used the "mean" (within "arrayfun") to illustrate the solution to your described problem:

testData = [1,  20, 33
            3,  23, 43
            2,  50, 32
            4,  13, 32
            4,  30, 15
            3,  33, 23
            1,  60, 12
            2,  24, 43 ];
       
catTestData = unique(testData(:,1));

outMean = [catTestData cell2mat(arrayfun(@(dIn) mean(testData(testData(:,1) == dIn,2:3),1),catTestData,'UniformOutput',false))];

Kind regards,

Robert

[Mohammad Aljarrah]

thank you very much Robert, that worked perfectly