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#!/usr/bin/env python
from scitools.std import *
# A simple contour plot of the peaks function:
contour(peaks())
figure()
# Here we draw 15 red contour lines with double line width:
xv, yv = ndgrid(linspace(-3,3,31),linspace(-3,3,31))
values = xv*exp(-xv**2-yv**2)
contour(xv, yv, values, 15, 'r', linewidth=2)
figure()
# Draw contour lines with labels at -2, 0, 2, and 5:
values = peaks(xv, yv)
contour(xv, yv, values, [-2,0,2,5])
figure()
# Here we combine a contour plot with a quiver plot (currently not
# working with the Gnuplot backend):
x = y = linspace(-2,2,21)
xv, yv = ndgrid(x, y, sparse=False)
values = sin(xv)*sin(yv)*exp(-xv**2 - xv**2)
dx, dy = gradient(values)
contour(xv, yv, values, 10, show=False)
hold('on')
quiver(xv, yv, dx, dy, 2, show=True)
hold('off')
figure()
# Another example:
x = linspace(-2,2,201)
y = linspace(-1,1,31)
xv, yv = ndgrid(x,y)
values = sin(3*yv - xv**2 + 1) + cos(2*yv**2 - 2*xv)
contour(xv,yv,values,clabels='on') # contour(x,y,values,..) also works
figure()
# The contourf command draws filled contours:
values = peaks(201)
contourf(values, 10, caxis=[-20, 20], title='Filled Contour Plot')
raw_input('Press Return key to quit: ')
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