Fix sklearn C type change (#795)

* use our (copied) RNG

* Update src/glum/_cd_fast.pyx

Co-authored-by: Uwe L. Korn <[email protected]>

---------

Co-authored-by: Uwe L. Korn <[email protected]>

src/glum/_cd_fast.pyx

@@ -17,23 +17,41 @@ from cython.parallel import prange
 import warnings
 from sklearn.exceptions import ConvergenceWarning
 
-from sklearn.utils._random cimport our_rand_r
-
 ctypedef np.float64_t DOUBLE
 ctypedef np.uint32_t UINT32_t
 
 np.import_array()
 
-
-# The following two functions are shamelessly copied from the tree code.
-
+# The following two functions are shamelessly copied from the tree code. (_random.pxd)
+# Authors: Arnaud Joly
+#
+# License: BSD-3-clause
 cdef enum:
     # Max value for our rand_r replacement (near the bottom).
     # We don't use RAND_MAX because it's different across platforms and
     # particularly tiny on Windows/MSVC.
     RAND_R_MAX = 0x7FFFFFFF
 
 
+# rand_r replacement using a 32bit XorShift generator
+# See http://www.jstatsoft.org/v08/i14/paper for details
+cdef inline UINT32_t our_rand_r(UINT32_t* seed) nogil:
+    """Generate a pseudo-random np.uint32 from a np.uint32 seed"""
+    # seed shouldn't ever be 0.
+    if (seed[0] == 0):
+        seed[0] = 1
+
+    seed[0] ^= <UINT32_t>(seed[0] << 13)
+    seed[0] ^= <UINT32_t>(seed[0] >> 17)
+    seed[0] ^= <UINT32_t>(seed[0] << 5)
+
+    # Use the modulo to make sure that we don't return a values greater than the
+    # maximum representable value for signed 32bit integers (i.e. 2^31 - 1).
+    # Note that the parenthesis are needed to avoid overflow: here
+    # RAND_R_MAX is cast to UINT32_t before 1 is added.
+    return seed[0] % ((<UINT32_t>RAND_R_MAX) + 1)
+
+
 cdef inline UINT32_t rand_int(UINT32_t end, UINT32_t* random_state) nogil:
     """Generate a random integer in [0; end)."""
     return our_rand_r(random_state) % end