masked_demo.py

#!/bin/env python
'''
Plot lines with points masked out.

This would typically be used with gappy data, to
break the line at the data gaps.
'''

import matplotlib.numerix.npyma as ma
from pylab import *

x = ma.arange(0, 2*pi, 0.02)
y = ma.sin(x)
y1 = sin(2*x)
y2 = sin(3*x)
ym1 = ma.masked_where(y1 > 0.5, y1)
ym2 = ma.masked_where(y2 < -0.5, y2)

lines = plot(x, y, 'r', x, ym1, 'g', x, ym2, 'bo')
setp(lines[0], linewidth = 4)
setp(lines[1], linewidth = 2)
setp(lines[2], markersize = 10)

legend( ('No mask', 'Masked if > 0.5', 'Masked if < -0.5') ,
        loc = 'upper right')
title('Masked line demo')
show()