import pyqtgraph as pg
from pyqtgraph.Qt import QtCore, QtGui
import numpy as np

win = pg.plot()

curves = [
    pg.PlotCurveItem(y=np.sin(np.linspace(0, 20, 1000)), pen='r', clickable=True),
    pg.PlotCurveItem(y=np.sin(np.linspace(1, 21, 1000)), pen='g', clickable=True),
    pg.PlotCurveItem(y=np.sin(np.linspace(2, 22, 1000)), pen='b', clickable=True),
]


def plotClicked(curve):
    global curves
    for i, c in enumerate(curves):
        if c is curve:
            c.setPen('rgb'[i], width=3)
        else:
            c.setPen('rgb'[i], width=1)


for c in curves:
    win.addItem(c)
    c.sigClicked.connect(plotClicked)

if __name__ == '__main__':
    import sys

    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()