# How to smoothen curves?

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Elysi Cochin on 14 Jun 2021
Answered: Image Analyst on 20 Jun 2021
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
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### Accepted Answer

Image Analyst on 20 Jun 2021
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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### More Answers (1)

KSSV on 14 Jun 2021
load('data')
x = data(:,1);
y = data(:,2:end);
figure(1),
plot(x, y,'r');
yi = zeros(size(y)) ;
for i = 1:size(y,2)
yi(:,i) = smooth(x,y(:,i)) ;
end
figure(2)
plot(x,yi,'k')
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Image Analyst on 20 Jun 2021
How does this not change rows 1, 20, and the last row?

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