[Python-Dev] os.path.walk() lacks 'depth first' option (original) (raw)

"Martin v. L�wis" martin@v.loewis.de
Mon, 21 Apr 2003 21:31:18 +0200

Noah Spurrier wrote:

I thought the names were synonymous, but a quick look on Google showed that post-order seems more specific to binary trees whereas depth first is more general, but I didn't look very hard and all my college text books are in storage :-) Depth first is more intuitive, but post order is more descriptive of what the algorithm does. If I were writing documentation (or reading it) I would prefer "depth first".

I'm tempted to declare this off-topic: depth-first means "traverse children before traversing siblings". Depth-first comes in three variations: pre-order (traverse node first, then children, then siblings), in-order (only for binary trees: traverse left child first, then node, then right child, then sibling), post-order (traverse children first, then node, then siblings). There is also breadth-first: traverse siblings first, then children.

I write these little directory/file filters quite often. I have come across this problem of renaming the directories you are traversing before.

I still can't understand why you can't use os.path.walk for that. Did you know that you can modify the list that is passed to the callback, and that walk will continue to visit the elements in the list?

Regards, Martin