How to take the average every 4 data points?
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First of all I have an array of 9536x1.
I would like to calculate the average value of every 4 data points and put the resulting values into a new array.
I guess using loop is the best solution for my quesiton but my understand is lacking at the moment.
For example,
Function [] = flitering(mydataset);
n = 0:1:(length(mydataset)/4)
for i=n
mean(mydataset(i+1:i+32,1));
end
If I would like to process 2 arrays at once would it be:
Function [] = flitering(mydataset,mydataset2);
n = 0:1:(length(mydataset)/4)
for i=n
mean(mydataset(i+1:i+32,1));
mean(mydataset2(i+1:i+32,1));
end
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采纳的回答
Star Strider
2022-11-14
v = (1:9536).';
vm = reshape(v, 4, [])
vMean4 = mean(vm)
In the event that the number of elements in the vector is not an exact multiple of 4:
v2 = (1:9535).';
cols = fix(numel(v2)/4)
v2m = reshape(v2(1:4*cols),4,[]);
v2Mean4 = mean(v2m)
v2(4*cols+1:end)
v2Mean4(end+1) = mean(v2(4*cols+1:end))
Check = v2Mean4(end)
.
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更多回答(4 个)
William Rose
2022-11-14
@민수,
I assume that you want a function that returns the average of points 1-4, then the average of points 5-8, then the average of points 9-12, and so on.
function y = filtering(x)
%FILTERING Compute 4-point moving average without overlap
n=floor(length(x)/4);
y=zeros(1,n);
for i=1:n
y(i)=sum(x(4*i-3:4*i))/4;
end
end
The floor() function enables filtering() to work without error, if the input vector has a length that is not a multiple of 4.
Example of usage:
>> x=sin(2*pi*(0:99)/100)+randn(1,100)/4;
>> y=filtering(x);
>> subplot(2,1,1); plot(x); subplot(2,1,2); plot(y)
It makes the figure below. The uppper plot is the unfiltered signal. The bottom plot is the filtered signal.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1192098/image.png)
Your results may vary, since randn() produces different random numbers with each call.
You can adjust the script as you wish, to make it process two vectors with a single call.
Good luck with your work.
1 个评论
Khushboo
2022-11-14
Hello,
You can try out the following instead of using a for loop:
n = 4; % calculate mean after every 4th data point
a = arrayfun(@(i) mean(mydataset(i:i+n-1)),1:n:length(mydataset)-n+1)'; % resulting vector
b = arrayfun(@(i) mean(mydataset2(i:i+n-1)),1:n:length(mydataset2)-n+1)';
Hope this helps!
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Askic V
2022-11-14
编辑:Askic V
2022-11-14
Just in case if you want to calculate mean/average of the elements in the last chunk (partition) that contains less that 4 elements, I would suggest the following code (example where last chunk contains 3 elements):
function mean_array = mean_chunk_array(arr, chunk_size)
chunk_size = 4;
nr_divisions = ceil(length(arr)/chunk_size);
mean_array = zeros(nr_divisions,1);
for ii = 0:nr_divisions-1
end_point = (ii+1)*chunk_size;
if end_point > length(arr)
end_point = length(arr);
end
mean_array(ii+1) = mean(arr(ii*chunk_size+1: end_point));
end
end
and call it like this:
arr = 1:27;
chunk_size = 4;
mean_arr = mean_chunk_array(arr, chunk_size)
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Delprat Sebastien
2024-6-24
There is a smooth function y=smooth(x,4)...
Simple and should be enough.
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