frange update

--HG--
branch : aspn

src/frange.py

@@ -1,6 +1,65 @@
+# http://code.activestate.com/recipes/577068-floating-point-range/
+
+def frange(*args):
+    """frange([start, ] end [, step [, mode]]) -> generator
+
+    A float range generator. If not specified, the default start is 0.0
+    and the default step is 1.0.
+
+    Optional argument mode sets whether frange outputs an open or closed
+    interval. mode must be an int. Bit zero of mode controls whether start is
+    included (on) or excluded (off); bit one does the same for end. Hence:
+
+        0 -> open interval (start and end both excluded)
+        1 -> half-open (start included, end excluded)
+        2 -> half open (start excluded, end included)
+        3 -> closed (start and end both included)
+
+    By default, mode=1 and only start is included in the output.
+    """
+    mode = 1  # Default mode is half-open.
+    n = len(args)
+    if n == 1:
+        args = (0.0, args[0], 1.0)
+    elif n == 2:
+        args = args + (1.0,)
+    elif n == 4:
+        mode = args[3]
+        args = args[0:3]
+    elif n != 3:
+        raise TypeError('frange expects 1-4 arguments, got %d' % n)
+    assert len(args) == 3
+    try:
+        start, end, step = [a + 0.0 for a in args]
+    except TypeError:
+        raise TypeError('arguments must be numbers')
+    if step == 0.0:
+        raise ValueError('step must not be zero')
+    if not isinstance(mode, int):
+        raise TypeError('mode must be an int')
+    if mode & 1:
+        i, x = 0, start
+    else:
+        i, x = 1, start+step
+    if step > 0:
+        if mode & 2:
+            from operator import le as comp
+        else:
+            from operator import lt as comp
+    else:
+        if mode & 2:
+            from operator import ge as comp
+        else:
+            from operator import gt as comp
+    while comp(x, end):
+        yield x
+        i += 1
+        x = start + i*step
+
+
 # http://code.activestate.com/recipes/66472/
 
-def frange(start, end=None, inc=None):
+def frange_(start, end=None, inc=None):
     "A range function, that does accept float increments..."
 
     if end == None: