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from scipy import arange, cos, linspace, randn, pi, sin
from scipy.sandbox.spline import splprep, splev
import matplotlib
matplotlib.use('WXAgg')
import pylab
# make ascending spiral in 3-space
t=linspace(0,1.75*2*pi,100)
x = sin(t)
y = cos(t)
z = t
# add noise
x+= 0.1*randn(*x.shape)
y+= 0.1*randn(*y.shape)
z+= 0.1*randn(*z.shape)
# spline parameters
s=3.0 # smoothness parameter
k=2 # spline order
nest=-1 # estimate of number of knots needed (-1 = maximal)
# find the knot points
tckp,u = splprep([x,y,z],s=s,k=k,nest=-1)
# evaluate spline, including interpolated points
xnew,ynew,znew = splev(linspace(0,1,400),tckp)
pylab.subplot(2,2,1)
data,=pylab.plot(x,y,'bo-',label='data')
fit,=pylab.plot(xnew,ynew,'r-',label='fit')
pylab.legend()
pylab.xlabel('x')
pylab.ylabel('y')
pylab.subplot(2,2,2)
data,=pylab.plot(x,z,'bo-',label='data')
fit,=pylab.plot(xnew,znew,'r-',label='fit')
pylab.legend()
pylab.xlabel('x')
pylab.ylabel('z')
pylab.subplot(2,2,3)
data,=pylab.plot(y,z,'bo-',label='data')
fit,=pylab.plot(ynew,znew,'r-',label='fit')
pylab.legend()
pylab.xlabel('y')
pylab.ylabel('z')
pylab.show()
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