MATLAB: How to smoothen curves

data smoothening

I have attached my data values
I plot it using the below code
load data
x = data(:,1);
y = data(:,2:end);
figure(2), plot(x, y, 'LineWidth', 2);
Without changing the 1st row, last row and 20th row of y-values, how to smoothen the data

Best Answer

Try this. Note the discontinuities at elements 1, 20, and 100 meaning the data was not changed for those elements. Change windowWidth to adjust the amount of smoothing.
load('data.mat')
x = data(:, 1); % x is in column 1
y = data(:, 2:end); % y is in columns 2 through 13.
nexttile;
plot(x, y,'-', 'LineWidth', 2);
grid on;
title('Original Data', 'FontSize', 20);
nexttile;
[rows, columns] = size(y)
windowWidth = 19; % Higher for more smoothing, smaller for less smoothing.
for col = 1 : columns
	% y is in columns.  Get the y in this column.
	thisy = y(:, col);
	% Smooth it.
    ySmooth = movmean(thisy, windowWidth);
	% Replace elements 1, 20, and end with the original values.
	ySmooth([1, 20, rows]) = thisy([1, 20, rows]);
	plot(x, ySmooth, '-', 'LineWidth', 2);
	hold on;
end
grid on;
hold off;
g = gcf;
g.WindowState = 'maximized';
% Indicate element #20
yl = ylim
line([x(20), x(20)], [0.72, yl(end)], 'LineWidth', 2, 'Color', 'r');
text(x(20), 0.72, ' Element 20', 'FontSize', 20, 'FontWeight', 'bold', 'Color', 'r');
title('Smoothed Data', 'FontSize', 20);
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