how to keep first 3 datas and obtain average, then skip or ignore the next 3 data and keep next 3 datas again....??

Hi all.

I have a 216 data in a one column from excel. but i want to keep first 3 datas and obtain average, then skip or ignore the next 3 data and keep next 3 datas again until finish 1:216, someone how to do that?

Answer 1

[Thiago Henrique Gomes Lobato]

An efficient way to do this is to create all the index that are going to belong to the average and then do it in a vectorized way. In your case, you can define each value belonging to the average with intervals of 6 values, an example can be done like this:

N = 15;
A = 1:N; % Simple vector to verify result, substitute by your A with N = 216

idx1 = 1:6:N;
idx2 = 2:6:N;
idx3 = 3:6:N;

Average = mean( [A(idx1);A(idx2);A(idx3)] )'

Average =

     2
     8
    14

[Eder Hernandez Martinez]

thanks Thiago for your response, but i think i didn't understand that i want, i mean...i have this data:

dat=dlmread('Copia de TORT103.csv',',',1,1);

v1=dat(5:end,9);

v1 =

0.0640

0.0630

0.0740

0.0720

0.0720

0.0430

0.0170

0.0090

0.0150

0.0170

0.0440

0.0220

0.0640

0.0680

0.0870

0.0730

0.0650

0.0620

...

until the end (217 datas) ....so, i want to keep "0.0640, 0.0630 and 0.0740" and ignore "0.0720, 0.0720 and 0.0430" and then keep "0.0430, 0.0170, 0.0090" and so on until I finish with my column.

[Thiago Henrique Gomes Lobato]

You use the same logic as my answer, in your exact case you can write

v1=dat(5:end,9);
N = size(v1,1);
idx1 = 1:6:N;
idx2 = 2:6:N;
idx3 = 3:6:N;

filteredv1=[v1(idx1),v1(idx2),v1(idx3)]';
filteredv1 = filteredv1(1:end)';
Averagev1 = mean( [v1(idx1),v1(idx2),v1(idx3)],2 );

[Eder Hernandez Martinez]

thanks a lot Thiago! you save my life!