ENH: using python's warnings instead of prints in fitpack.

When fitpack detects a recoverable problem, it will signal it with
a RuntimeWarning instead of printing to stdout. This way the output
can be programatically silenced or made exceptions.

scipy/interpolate/fitpack.py

@@ -21,12 +21,13 @@
     For univariate splines: cocosp, concon, fourco, insert
     For bivariate splines: profil, regrid, parsur, surev
 """
-from __future__ import division, print_function, absolute_import
+from __future__ import division, absolute_import
 
 
 __all__ = ['splrep', 'splprep', 'splev', 'splint', 'sproot', 'spalde',
     'bisplrep', 'bisplev', 'insert', 'splder', 'splantider']
 
+import warnings
 import numpy as np
 from . import _fitpack
 from numpy import atleast_1d, array, ones, zeros, sqrt, ravel, transpose, \
@@ -229,7 +230,7 @@ def splprep(x,w=None,u=None,ub=None,ue=None,k=3,task=0,s=None,t=None,
         for i in range(idim):
             if x[i][0] != x[i][-1]:
                 if quiet < 2:
-                    print('Warning: Setting x[%d][%d]=x[%d][0]' % (i,m,i))
+                    warnings.warn(RuntimeWarning('Setting x[%d][%d]=x[%d][0]' % (i,m,i)))
                 x[i][-1] = x[i][0]
     if not 0 < idim < 11:
         raise TypeError('0 < idim < 11 must hold')
@@ -295,11 +296,12 @@ def splprep(x,w=None,u=None,ub=None,ue=None,k=3,task=0,s=None,t=None,
     c.shape = idim,n-k-1
     tcku = [t,list(c),k],u
     if ier <= 0 and not quiet:
-        print(_iermess[ier][0])
-        print("\tk=%d n=%d m=%d fp=%f s=%f" % (k,len(t),m,fp,s))
+        warnings.warn(RuntimeWarning(_iermess[ier][0] +
+                                     "\tk=%d n=%d m=%d fp=%f s=%f" %
+                                     (k, len(t), m, fp, s)))
     if ier > 0 and not full_output:
         if ier in [1,2,3]:
-            print("Warning: "+_iermess[ier][0])
+            warnings.warn(RuntimeWarning(_iermess[ier][0]))
         else:
             try:
                 raise _iermess[ier][1](_iermess[ier][0])
@@ -498,11 +500,12 @@ def splrep(x,y,w=None,xb=None,xe=None,k=3,task=0,s=None,t=None,
         n,c,fp,ier = dfitpack.percur(task, x, y, w, t, wrk, iwrk, k, s)
     tck = (t[:n],c[:n],k)
     if ier <= 0 and not quiet:
-        print(_iermess[ier][0])
-        print("\tk=%d n=%d m=%d fp=%f s=%f" % (k,len(t),m,fp,s))
+        warnings.warn(RuntimeWarning(_iermess[ier][0]) +
+                               "\tk=%d n=%d m=%d fp=%f s=%f" %
+                               (k, len(t), m, fp, s))
     if ier > 0 and not full_output:
         if ier in [1,2,3]:
-            print("Warning: "+_iermess[ier][0])
+            warnings.warn(RuntimeWarning(+_iermess[ier][0]))
         else:
             try:
                 raise _iermess[ier][1](_iermess[ier][0])
@@ -723,7 +726,7 @@ def sproot(tck,mest=10):
         if ier == 0:
             return z
         if ier == 1:
-            print("Warning: the number of zeros exceeds mest")
+            warnings.warn(RuntimeWarning("The number of zeros exceeds mest"))
             return z
         raise TypeError("Unknown error")
 
@@ -951,14 +954,14 @@ def bisplrep(x,y,z,w=None,xb=None,xe=None,yb=None,ye=None,kx=3,ky=3,task=0,
 
     ierm = min(11,max(-3,ier))
     if ierm <= 0 and not quiet:
-        print(_iermess2[ierm][0])
-        print("\tkx,ky=%d,%d nx,ny=%d,%d m=%d fp=%f s=%f" % (kx,ky,len(tx),
-                                                           len(ty),m,fp,s))
+        warnings.warn(RuntimeWarning(_iermess2[ierm][0]) +
+                                 "\tkx,ky=%d,%d nx,ny=%d,%d m=%d fp=%f s=%f" %
+                                 (kx, ky, len(tx), len(ty), m, fp, s))
     if ierm > 0 and not full_output:
         if ier in [1,2,3,4,5]:
-            print("Warning: "+_iermess2[ierm][0])
-            print("\tkx,ky=%d,%d nx,ny=%d,%d m=%d fp=%f s=%f" % (kx,ky,len(tx),
-                                                           len(ty),m,fp,s))
+            _mess = "\n\tkx,ky=%d,%d nx,ny=%d,%d m=%d fp=%f s=%f" % (kx,ky,len(tx),
+                                                                     len(ty),m,fp,s)
+            warnings.warn(RuntimeWarning(_iermess2[ierm][0] + _mess))
         else:
             try:
                 raise _iermess2[ierm][1](_iermess2[ierm][0])