How do I calculate the average of a vector of double and how do I calculate the variance of a vector of double?
MATLAB: Average and variance of a double array
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Again, I'm not sure what this means or if it is really what you want but I think it's what you described.
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 20;% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');baseFileName = 'cameraman.tif';fullFileName = fullfile(folder, baseFileName);% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);if ~exist(fullFileName, 'file') % Didn't find it there. Check the search path for it.
fullFileName = baseFileName; % No path this time.
if ~exist(fullFileName, 'file') % Still didn't find it. Alert user.
errorMessage = sprintf('Error: %s does not exist.', fullFileName); uiwait(warndlg(errorMessage)); return; endendgrayImage = imread(fullFileName);% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);% Display the original gray scale image.
subplot(2, 3, 1);imshow(grayImage, []);title('Original Grayscale Image', 'FontSize', fontSize);% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') % Calculate the standard deviation image.
sdImage = stdfilt(grayImage);% Display the image.
subplot(2, 3, 2);imshow(sdImage, []);title('Std. Dev. Image', 'FontSize', fontSize);% Calculate the variance image.
varianceImage = sdImage .^2;% Display the image.subplot(2, 3, 3);imshow(varianceImage, []);title('Variance Image', 'FontSize', fontSize);% Calculate the mean of the variance image in a 3x3 region.
% Basically this is a blurred version of it.
meanVarianceImage = conv2(varianceImage, ones(3)/9);% Display the image.subplot(2, 3, 4);imshow(meanVarianceImage, []);title('Mean Variance Image', 'FontSize', fontSize);for gl = 0:255 % Find pixels in the original image with this gray level.
matchingIndexes = (grayImage == gl); % Get the mean of only those pixels from the mean variance image.
W(gl+1) = mean(meanVarianceImage(matchingIndexes));end% Plot W
subplot(2, 3, 5);plot(W);grid on;title('Plot of W', 'FontSize', fontSize);xlabel('Gray Level', 'FontSize', fontSize);data - your array [42x16384]
EDIT
out = mean(reshape(data,size(data,1),[],8),3);eg:
data - your array [55x72000]
out = mean(reshape(data,size(data,1),[],3),3);or
out = squeeze(mean(reshape(data,size(data,1),3,[]),2)) ;
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