more re-enstating of some preiov commits.

GPy/kern/__init__.py

@@ -2,5 +2,9 @@
 # Licensed under the BSD 3-clause license (see LICENSE.txt)
 
 
-from constructors import rbf, Matern32, Matern52, exponential, linear, white, bias, finite_dimensional, spline, Brownian, rbf_sympy, sympykern, periodic_exponential, periodic_Matern32, periodic_Matern52, prod, prod_orthogonal, symmetric, coregionalise, rational_quadratic, fixed, rbfcos
+from constructors import rbf, Matern32, Matern52, exponential, linear, white, bias, finite_dimensional, spline, Brownian, periodic_exponential, periodic_Matern32, periodic_Matern52, prod, prod_orthogonal, symmetric, coregionalise, rational_quadratic, fixed, rbfcos, independent_outputs
+try:
+    from constructors import rbf_sympy, sympykern # these depend on sympy
+except:
+    pass
 from kern import kern

GPy/kern/constructors.py

@@ -25,6 +25,7 @@ from symmetric import symmetric as symmetric_part
 from coregionalise import coregionalise as coregionalise_part
 from rational_quadratic import rational_quadratic as rational_quadraticpart
 from rbfcos import rbfcos as rbfcospart
+from independent_outputs import independent_outputs as independent_output_part
 #TODO these s=constructors are not as clean as we'd like. Tidy the code up
 #using meta-classes to make the objects construct properly wthout them.
 
@@ -165,10 +166,15 @@ def Brownian(D,variance=1.):
     part = Brownianpart(D,variance)
     return kern(D, [part])
 
+try:
     import sympy as sp
     from sympykern import spkern
     from sympy.parsing.sympy_parser import parse_expr
+    sympy_available = True
+except ImportError:
+    sympy_available = False
 
+if sympy_available:
     def rbf_sympy(D,ARD=False,variance=1., lengthscale=1.):
         """
         Radial Basis Function covariance.
@@ -193,6 +199,7 @@ def sympykern(D,k):
         A kernel from a symbolic sympy representation
         """
         return kern(D,[spkern(D,k)])
+del sympy_available
 
 def periodic_exponential(D=1,variance=1., lengthscale=None, period=2*np.pi,n_freq=10,lower=0.,upper=4*np.pi):
     """
@@ -318,3 +325,14 @@ def rbfcos(D,variance=1.,frequencies=None,bandwidths=None,ARD=False):
     """
     part = rbfcospart(D,variance,frequencies,bandwidths,ARD)
     return kern(D,[part])
+
+def independent_outputs(k):
+    """
+    Construct a kernel with independent outputs from an existing kernel
+    """
+    for sl in k.input_slices:
+        assert (sl.start is None) and (sl.stop is None), "cannot adjust input slices! (TODO)"
+    parts = [independent_output_part(p) for p in k.parts]
+    return kern(k.D+1,parts)
+
+