How to average in rows of two numbers

Hi all,

I have a matrix of 1*305, I want to take the average of two rows like (1st row to 4th row) and (2nd row to 5th row) and (3rd row to 6th row) and (7th row to 10th row) and (8th row to 11th row) and (9th row to 12 row) and soo on. I want to take average in this way, can anyone help me out.

Thankyou

Answer 1

[Star Strider]

If I understand correctly what you want to do, this will work:

D = load('AI_Aorta.mat');
x = D.x;
idx = hankel(1:4, 4:numel(x));                          % Index Matrix
xm = mean(x(idx));                                      % Mean Of Columns Of Resulting Matrix

To understand what this code does and how it works:

Check_First_Five_Columns = x(idx(:,1:5))                % The 'xm' Variable Is The Mean Of The Columns Of This Matrix (Extended To 302 Columns)

producing:

Check_First_Five_Columns =
    0.1247    0.2370    0.1695    0.2010    0.2228
    0.2370    0.1695    0.2010    0.2228    0.1482
    0.1695    0.2010    0.2228    0.1482    0.1683
    0.2010    0.2228    0.1482    0.1683    0.2063

[Lokeswara reddy pamulapate]

it worked, And one more as I said for 305 points if we take average of only two points then we get a matrix of 1*153 points right.

I dont need extra rows I only need 1 column with the average of two numbers that is 1 and 4th column average I get only one point, and 2nd and 5th column I get only one point and 3rd and 6th I get one point total for first 6 columns i get 3 points from those average.. so in total I only have 153 points from 305 points.

This is my question sorry for not explaining correctly.

[Star Strider]

Your original Question was ‘... (1st row to 4th row) and (2nd row to 5th row) ...’ (underlines added) so I took those to be inclusive of the numbers between the 1st and 4th, 2nd and 5th, and so forth.

If you only want the mean values of the 1st and 4th, 2nd and 5th, 3rd and 6th, ... one minor change in my code will do that. The revised full code is now:

D = load('AI_Aorta.mat');
x = D.x;
idx = hankel(1:4, 4:numel(x));                          % Index Matrix
idx2 = idx([1 4],:);                                    % Revised Index Matrix
xm = mean(x(idx2));                                     % Mean Of Columns Of Resulting Matrix

and:

Check = x(idx2(:,1:5))                                  % The ‘xm’ Variable Is The Mean Of The Columns Of This Matrix (Extended To 302 Columns)

producing:

Check =
    0.1247    0.2370    0.1695    0.2010    0.2228    ...
    0.2010    0.2228    0.1482    0.1683    0.2063    ...

with ‘xm’ again being a (1x302) element vector.

[Lokeswara reddy pamulapate]

I am getting the result, but I only need 153 values out of 305, I want the average of two numbers in one. that is 1st column to 4th column is one value which is stored in 1st column and 2nd column to 5th column is one value which is stored in 2nd column and 3rd column to 6th column is one value which is stored in 3rd column and 7th column to 10th column is one value which is stored in 4th column and 8th column to 11th column which is one value which is stored in 5th column and 9th column to 12th column which is one value which is stored in 6th column and 13th column to 16th column is one value which is stored in 7th column and 14t column to 17th column is one value which is stored in 8th column and 15th column to 18th column is one value which is stored in 9th column and soo on.

I want the average of 1st three columns values to 2nd three columns and the 2nd three must not be taken again and next I want to take average of values from 7,8,9 to 10,11,12 and next 13,14,15 to 16,17,18 in this way I will get the average of values in a matrix value 1*152 like that.

[Star Strider]

I am lost.

xm = filter([1 0 0 1], 2, x(1:153));                    % Column Mean