predicate equality is fuzzy with float precision tolerance

Author: papajohn

datascience/predicates.py

@@ -1,6 +1,8 @@
 """Predicate functions."""
 
 import functools
+import numbers
+import numpy as np
 
 __all__ = ['are']
 
@@ -81,7 +83,7 @@ class are:
     @staticmethod
     def equal_to(y):
         """Equal to y."""
-        return _combinable(lambda x: x == y)
+        return _combinable(lambda x: _equal_or_float_equal(x, y))
 
     @staticmethod
     def above(y):
@@ -96,12 +98,12 @@ def below(y):
     @staticmethod
     def above_or_equal_to(y):
         """Greater than or equal to y."""
-        return _combinable(lambda x: x >= y)
+        return _combinable(lambda x: x >= y or _equal_or_float_equal(x, y))
 
     @staticmethod
     def below_or_equal_to(y):
         """Less than or equal to y."""
-        return _combinable(lambda x: x <= y)
+        return _combinable(lambda x: x <= y or _equal_or_float_equal(x, y))
 
     @staticmethod
     def strictly_between(y, z):
@@ -111,12 +113,12 @@ def strictly_between(y, z):
     @staticmethod
     def between(y, z):
         """Greater than or equal to y and less than z."""
-        return _combinable(lambda x: y <= x < z)
+        return _combinable(lambda x: (y <= x < z) or _equal_or_float_equal(x, y))
 
     @staticmethod
     def between_or_equal_to(y, z):
         """Greater than or equal to y and less than or equal to z."""
-        return _combinable(lambda x: y <= x <= z)
+        return _combinable(lambda x: (y <= x <= z) or _equal_or_float_equal(x, y) or _equal_or_float_equal(x, z))
 
 ###############
 # Combination #
@@ -150,6 +152,12 @@ def __xor__(self, other):
 def _not(f):
     return lambda *args: -f(*args)
 
+def _equal_or_float_equal(x, y):
+    if isinstance(x, numbers.Real):
+        return x == y or np.nextafter(x, 1) == y or np.nextafter(x, 0) == y
+    else:
+        return x == y
+
 are.not_equal_to = _not(are.equal_to)
 are.not_above = are.below_or_equal_to
 are.not_below = are.above_or_equal_to