SmoothBivariateSpline giving wrong result
Hi all, I am trying to do a 2d interpolation of unstructured data. To try to get a feel for how the functions work, I tried a simple test case and it is not working. See below: In [24]: x = numpy.arange(10.) In [25]: y = numpy.arange(10.) In [26]: z = x**2 + y**2 In [27]: fcn = SmoothBivariateSpline(x,y,z, s=0, kx=1, ky=1) In [28]: fcn(1,1) Out[28]: array([[ 0.]]) In [29]: fcn(1,5) Out[29]: array([[ 0.]]) What am I doing wrong? It seems like z should be a 2d array or something, but the documentation explicitly says it is a 1d array. Much thanks, and I look forward to feeling stupid! Kevin Gullikson
On Mon, Oct 15, 2012 at 11:19 PM, Kevin Gullikson <kevin.gullikson@gmail.com> wrote:
Hi all,
I am trying to do a 2d interpolation of unstructured data. To try to get a feel for how the functions work, I tried a simple test case and it is not working. See below:
In [24]: x = numpy.arange(10.)
In [25]: y = numpy.arange(10.)
In [26]: z = x**2 + y**2
In [27]: fcn = SmoothBivariateSpline(x,y,z, s=0, kx=1, ky=1)
In [28]: fcn(1,1) Out[28]: array([[ 0.]])
In [29]: fcn(1,5) Out[29]: array([[ 0.]])
What am I doing wrong? It seems like z should be a 2d array or something, but the documentation explicitly says it is a 1d array.
1d is fine but you need points that cover an area in R^2 not just a line, diagonal from 0 to 10
x,y = np.meshgrid(np.arange(10.), np.arange(10.)) x.shape (10, 10)
x = x.flatten() y = y.flatten() z = x**2 + y**2 z.shape (100,) from scipy.interpolate import SmoothBivariateSpline fcn = SmoothBivariateSpline(x,y,z, s=0, kx=1, ky=1) fcn(1, 1) array([[ 2.41605245]]) fcn(1, 5) array([[ 26.03716212]])
Josef
Much thanks, and I look forward to feeling stupid! Kevin Gullikson
_______________________________________________ SciPy-User mailing list SciPy-User@scipy.org http://mail.scipy.org/mailman/listinfo/scipy-user
On Tue, Oct 16, 2012 at 7:32 PM, <josef.pktd@gmail.com> wrote:
On Mon, Oct 15, 2012 at 11:19 PM, Kevin Gullikson <kevin.gullikson@gmail.com> wrote:
Hi all,
I am trying to do a 2d interpolation of unstructured data. To try to get a feel for how the functions work, I tried a simple test case and it is not working. See below:
In [24]: x = numpy.arange(10.)
In [25]: y = numpy.arange(10.)
In [26]: z = x**2 + y**2
In [27]: fcn = SmoothBivariateSpline(x,y,z, s=0, kx=1, ky=1)
In [28]: fcn(1,1) Out[28]: array([[ 0.]])
In [29]: fcn(1,5) Out[29]: array([[ 0.]])
What am I doing wrong? It seems like z should be a 2d array or something, but the documentation explicitly says it is a 1d array.
1d is fine but you need points that cover an area in R^2 not just a line, diagonal from 0 to 10
x,y = np.meshgrid(np.arange(10.), np.arange(10.)) x.shape (10, 10)
x = x.flatten() y = y.flatten() z = x**2 + y**2 z.shape (100,) from scipy.interpolate import SmoothBivariateSpline fcn = SmoothBivariateSpline(x,y,z, s=0, kx=1, ky=1) fcn(1, 1) array([[ 2.41605245]]) fcn(1, 5) array([[ 26.03716212]])
I don't remember how kx, ky are defined this actually fits through the points:
fcn = SmoothBivariateSpline(x,y,z, s=0, kx=2, ky=2) fcn(1, 1) array([[ 2.]]) fcn(1, 5) array([[ 26.]]) fcn(2,2) array([[ 8.]])
Josef
Josef
Much thanks, and I look forward to feeling stupid! Kevin Gullikson
_______________________________________________ SciPy-User mailing list SciPy-User@scipy.org http://mail.scipy.org/mailman/listinfo/scipy-user
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