How do I take the average of every n values in a vector?

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Brooks
Brooks 2013-6-27
评论： Laukik Avinash Kharche 2022-7-1
I have some data on Pulse Rate and the sample was taken at 1000 Hz (One sample every millisecond), way too big for what I want to see. My vector is 399277x1 and I want to be able to average every 1000 values and get that number in a new vector of somewhere around 400x1. Is there any way to do this?
Thanks

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Matthew Eicholtz
Matthew Eicholtz 2013-6-27
Try this...
n = 1000; % average every n values
a = reshape(cumsum(ones(n,10),2),[],1); % arbitrary data
b = arrayfun(@(i) mean(a(i:i+n-1)),1:n:length(a)-n+1)'; % the averaged vector
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Jan
Jan 2013-6-28
编辑：Jan 2019-5-17
x = rand(399277, 1); % Some example data
n = 1000; % Number of elements to create the mean over
s1 = size(x, 1); % Find the next smaller multiple of n
m = s1 - mod(s1, n);
y = reshape(x(1:m), n, []); % Reshape x to a [n, m/n] matrix
Avg = transpose(sum(y, 1) / n); % Calculate the mean over the 1st dim
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Image Analyst
Image Analyst 2013-6-27
编辑：Image Analyst 2019-1-5
Here is how I'd do it (an alternate way), using blockproc to average in 100 element long blocks in "jumps":
% Create sample data
PulseRateF = rand(399277, 1);
% Define the block parameter. Average in a 100 row by 1 column wide window.
blockSize = [1000, 1];
% Block process the image to replace every element in the
% 100 element wide block by the mean of the pixels in the block.
% First, define the averaging function for use by blockproc().
meanFilterFunction = @(theBlockStructure) mean2(theBlockStructure.data(:));
% Now do the actual averaging (block average down to smaller size array).
blockAveragedDownSignal = blockproc(PulseRateF, blockSize, meanFilterFunction);
% Let's check the output size.
[rows, columns] = size(blockAveragedDownSignal)
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Stelios Fanourakis
Stelios Fanourakis 2019-5-16
编辑：Stelios Fanourakis 2019-5-16
I am not sure whether I understood it well. I use this
% Create sample data
PulseRateF = Pd;
% Define the block parameter. Average in a 100 row by 1 column wide window.
blockSize = [300, 100];
% Block process the image to replace every element in the
% 100 element wide block by the mean of the pixels in the block.
% First, define the averaging function for use by blockproc().
meanFilterFunction = @(theBlockStructure) mean2(theBlockStructure.data(:));
% Now do the actual averaging (block average down to smaller size array).
blockAveragedDownSignal = blockproc(PulseRateF, blockSize, meanFilterFunction);
% Let's check the output size.
[rows, columns] = size(blockAveragedDownSignal)
And I get
rows = 5 columns = 1
What those numbers mean?
Jan
Jan 2019-5-16
Look at the code: These numbers are the size of the variable blockAveragedDownSignal.

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Andrei Bobrov
Andrei Bobrov 2013-6-28
编辑：Andrei Bobrov 2017-7-28
x = randi(1000,399277,1);
n = 1000;
m = numel(x);
out = nanmean(reshape( [x(:);nan(mod(-m,n),1)],n,[]));
or
out = accumarray(ceil((1:numel(x))/1000)',x(:),[],@mean);
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Stelios Fanourakis
Stelios Fanourakis 2019-5-13
@Andrei Bobrov
What this actually does? Does it average in a step of n intervals along the x axis? This is what I am looking for. Hope this does what I want.
I want to divide the x axis into intervals and average between them.

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Aubai
Aubai 2017-1-20

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