feat: value_in_interval

lkj/__init__.py

@@ -14,6 +14,7 @@
     wrapped_print,
 )
 from lkj.importing import import_object, register_namespace_forwarding
+from lkj.misc import identity, value_in_interval
 
 ddir = lambda obj: list(filter(lambda x: not x.startswith('_'), dir(obj)))
 

lkj/misc.py

@@ -0,0 +1,49 @@
+"""Miscellaneous tools."""
+
+from operator import attrgetter, ge, gt, le, lt
+from functools import partial
+from typing import Callable, T, Optional, Any
+
+
+def identity(x):
+    return x
+
+
+def value_in_interval(
+    x: Any = None,
+    /,
+    *,
+    get_val: Callable[[Any], T] = identity,
+    min_val: Optional[T] = None,
+    max_val: Optional[T] = None,
+    is_minimum: Callable[[T, T], bool] = ge,
+    is_maximum: Callable[[T, T], bool] = lt,
+):
+    """
+
+    >>> from operator import itemgetter, le
+    >>> f = value_in_interval(get_val=itemgetter('date'), min_val=2, max_val=8)
+    >>> d = [{'date': 1}, {'date': 2}, {'date': 3, 'x': 7}, {'date': 8}, {'date': 9}]
+    >>> list(map(f, d))
+    [False, True, True, False, False]
+
+    The default `is_maximum` is `lt` (i.e. lambda x: x < max_val). If you want to
+    use `le` (i.e. lambda x: x <= max_val) you can change the is_maximum argument:
+
+    >>> ff = value_in_interval(
+    ...     get_val=itemgetter('date'), min_val=2, max_val=8, is_maximum=le
+    ... )
+    >>> list(map(ff, d))
+    [False, True, True, True, False]
+    """
+    if x is None:
+        kwargs = locals()
+        kwargs.pop('x')
+        return partial(value_in_interval, **kwargs)
+    else:
+        val = get_val(x)
+        if min_val is not None and not is_minimum(val, min_val):
+            return False
+        if max_val is not None and not is_maximum(val, max_val):
+            return False
+        return True