Mean value of a subarray

Hi all

i have an array V=1x115 i want to create another array which contains the mean value neatly of the first 8 V values than of the subsequent 8 and so on... in pratical terms: mean(V(1:8)), mean(V(8:16)),...mean(V(112:end))

Thank you for the help

Regards

[Adam Danz]

1:8 contains 8 values.

8:16 contains 9 values.

If you meant to write 1:8 and 8:15 (each containing 8 values), see my answer.

If you meant to write 1:8, 9:16 (each containing 8-values), see the link at the top of my answer.

If your window sizes vary, you'll need to explain your problem with more detail.

[EldaEbrithil]

Thank you Adam

I solved the problem thanks to your upper link, now i understand the logic for the moving average

Regards

Answer 1

[Adam Danz]

The answer in this link computes segmented averages as you describe except instead of averaging 1:8, 8:15, ... , it averages 1:8, 9:16, ..., .

Solution

To replicate the edges, you just have to add three line.

The full solutions is shown in this demo.

data = 1:22; % Demo data
winSz = 5;   % Window size; winSz=5 results in indices of (1:5, 5:9, 9:13, ...)

replications = repmat([2;ones(winSz-2,1)],ceil(numel(data)/(winSz-1)),1); 
dataPrep = repelem(data(:),replications(1:numel(data)));
dataPrep(1) = []; % do not duplicate 1st datapoint

% Reshape dataPrep into matrix.
% NOTE: 'dataPrep' must contain a number of element divisibly by 'winSz'.
% Otherwise, 'dataPrep' will be padded with NaN values so that it is 
% divisible by 'winSz'.
if rem(numel(dataPrep),winSz)>0
    nanAppend = nan(winSz - rem(numel(dataPrep),winSz),1);
else
    nanAppend = [];
end
dataMat = reshape([dataPrep; nanAppend], winSz, []);
movingAverage = mean(dataMat,1,'Omitnan');

Results

The original data:

data =
  Columns 1 through 20
     1     2     3     4     5     6     7     8     9    10    11    12    13    14    15    16    17    18    19    20
  Columns 21 through 22
    21    22

The blocked version where means are computed over each column

dataMat =
     1     5     9    13    17    21
     2     6    10    14    18    22
     3     7    11    15    19   NaN
     4     8    12    16    20   NaN
     5     9    13    17    21   NaN

The means (within a 5-element window)

movingAverage =
            3  7  11  15  19  21.5

[EldaEbrithil]

Thank you Adam!! This is brilliant!!

[Adam Danz]

Socially distant high five!

[EldaEbrithil]

Ahahah xD