make my data less noisy and add a legend in matlab

To make your data less noisy in MATLAB, you can apply various filtering techniques such as moving average, median filter, or low-pass filter based on your data characteristics. Here is an example of applying a moving average filter to a noisy signal x to reduce noise:

main.m
% Apply a moving average filter with window size 5 and plot the noisy and filtered signals
x_filtered = movmean(x,5); % Apply moving average filter
figure;
plot(x,'b'); hold on;
plot(x_filtered,'r');
legend({'Noisy signal','Filtered signal'})
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To add a legend to a plot in MATLAB, you can use the legend function. The input argument to the legend function is a cell array of strings representing the labels for each plot. The order of the labels should match the order of the plots in your plot() function.

In the above example code, we added a legend to the plot using legend({'Noisy signal','Filtered signal'}) where the first label corresponds to the blue signal, and the second label corresponds to the red filtered signal.

Note that you can customize the location, font, and other properties of the legend by passing additional input arguments to the legend function.