I am trying to plot eeg data of 6 channels. Three channels are within the same area and other three channels are from another area. So I differentiate them with two colours. However, as I have 6 lines in overall I am able to display only a legend for 6 lines - 3 blue, 3 red, and not legend for 2 colours - blue for one area, red for the other one.
How can I change the legend so I would have only 2 descriptions - one for blue and one for red, please??