How to smoothen curves?

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

Answer 1

[Image Analyst]

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);

Answer 2

[KSSV]

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')

[KSSV]

Use indexing.. M

[Image Analyst]

How does this not change rows 1, 20, and the last row?