X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=string_utils.py;h=a766adabe97ffc8432a9bda280c66107634bc52b;hb=1ee64f3522abbbc2df154c8f44be87929a16e17e;hp=4bec031738e989d10507992387e18aa47996da8e;hpb=f2600f30801c849fc1d139386e3ddc3c9eb43e30;p=python_utils.git

diff --git a/string_utils.py b/string_utils.py
index 4bec031..a766ada 100644
--- a/string_utils.py
+++ b/string_utils.py
@@ -1649,7 +1649,7 @@ def ip_v4_sort_key(txt: str) -> Optional[Tuple[int, ...]]:
     if not is_ip_v4(txt):
         print(f"not IP: {txt}")
         return None
-    return tuple([int(x) for x in txt.split('.')])
+    return tuple(int(x) for x in txt.split('.'))
 
 
 def path_ancestors_before_descendants_sort_key(volume: str) -> Tuple[str, ...]:
@@ -1664,7 +1664,7 @@ def path_ancestors_before_descendants_sort_key(volume: str) -> Tuple[str, ...]:
     ['/usr', '/usr/local', '/usr/local/bin']
 
     """
-    return tuple([x for x in volume.split('/') if len(x) > 0])
+    return tuple(x for x in volume.split('/') if len(x) > 0)
 
 
 def replace_all(in_str: str, replace_set: str, replacement: str) -> str:
@@ -1680,6 +1680,20 @@ def replace_all(in_str: str, replace_set: str, replacement: str) -> str:
     return in_str
 
 
+def replace_nth(string: str, source: str, target: str, nth: int):
+    """Replaces the nth occurrance of a substring within a string.
+
+    >>> replace_nth('this is a test', ' ', '-', 3)
+    'this is a-test'
+
+    """
+    where = [m.start() for m in re.finditer(source, string)][nth - 1]
+    before = string[:where]
+    after = string[where:]
+    after = after.replace(source, target, 1)
+    return before + after
+
+
 if __name__ == '__main__':
     import doctest