Setting multiple axvspan labels as one element in legend

Question

I am trying to set up a series of vertical axis spans to symbolize different switching positions at different times. For example, in the figure below, switching position 1 (green) happens quite a few times, alternating between other positions.

I plot these spans running a for loop in a list of tuples, each containing the initial and final indexes of each interval to plot the axvspan.

def plotShades(timestamp, intervals, colour):
    for i in range(len(intervals)):
        md.plt.axvspan(timestamp[intervals[i][0]], timestamp[intervals[i][1]], alpha=0.5, color=colour, label="interval")

This function is then called upon another one, that plots the shades for each different switching position:

def plotAllOutcomes(timestamp, switches):
    #switches is a list of 7 arrays indicating when the switcher is at each one of the 7 positions. If the array has a 1 value, the switcher is there. 0 otherwise.

    colors = ['#d73027', '#fc8d59', '#fee08b', '#ffffbf', '#d9ef8b', '#91cf60', '#1a9850']     
    intervals = []        

    for i in range(len(switches)):
        intervals.append(getIntervals(switches[i], timestamp))
        plotShades(timestamp, intervals[i], colors[i])    
        md.plt.legend()

Doing so with the code snippets I've put here (not the best code, I know - I'm fairly new in Python!) the legend ends up having one item for each interval, and that's pretty awful. This is how it looks:

I'd like to get a legend with only 7 items, each for a single color in my plot of axvspans. How can I proceed to do so? I've searched quite extensively but haven't managed to find this situation being asked before. Thank you in advance for any help!!

Answer 1

A small trick you can apply using the fact that labels starting with "_" are ignored:

plt.axvspan( ... , label =  "_"*i + "interval")

Thereby a label is only created for the case where i==0.