I have 974 data points located on the surface of the unit sphere. The points are not ordered in any particular way. I wish to read in these data points, along with their corresponding polar coordinates (phi, theta). I then wish to interpolate onto a regular latitude-longitude grid using scipy.interpolate.SmoothSphereBivariateSpline. So far I have the following code:
import numpy as np
from scipy.interpolate import SmoothSphereBivariateSpline
#Read in the unorganized grid points
# and also shift so that phi in [0,pi] and theta in [0,2*pi)
leb = np.genfromtxt('grid.txt')
u, v = np.hsplit(leb, 2)
phi, theta = u[:,0], v[:,0]
theta += np.pi
#Read in the unorganized data values
data1 = np.genfromtxt('0p0_97p03.txt')
#Create the interpolator object
lut = SmoothSphereBivariateSpline(phi, theta, data1, s=350)
#Generate a regular lat-long grid to interpolate onto
N = 100
lat = np.linspace(0.0, np.pi, N)
lon = np.linspace(0.0, 2.0*np.pi, N)
lat, lon = np.meshgrid(lat, lon)
#Now interpolate onto the regular grid
data_inerp = lut(lat, lon)
In the above code, the arrays phi, theta and data1 are the unorganized data points, with each of these three arrays having a shape (974,). When i run this code I get the error message: Traceback (most recent call last):
File "spherebiv.py", line 25, in <module>
data_inerp = lut(lat, lon)
File "/usr/lib/python2.7/dist-packages/scipy/interpolate/fitpack2.py", line 958, in __call__
raise ValueError("Error code returned by bispev: %s" % ier)
ValueError: Error code returned by bispev: 10
Now I don't understand this error code - it seems to be something to do with the underlying Fortran routine. Is there anything obvious I'm doing wrong here?
