Steal the algorithm used to combine hashes from tupleobject.c #15227
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Contributor
Author
|
Here's an initial pass at stealing https://github.com/python-git/python/blob/master/Objects/tupleobject.c#L290 for the combining. I am not 100% that the problem is my (rather crude) combiner, but possibly the exact way we're using the bitmixer in hash_array. I'm trying to think about it........I think we might be maintaining undesirable linearity. May I ask, how did you encounter these collisions? |
Contributor
Author
|
If the basic approach looks sound I can add some comments around some of the lazy iterator wackiness. |
jreback
reviewed
Jan 25, 2017
pandas/tools/hashing.py
Outdated
| arrays = itertools.chain([first], arrays) | ||
|
|
||
| mult = np.zeros_like(first) + np.uint64(1000003) | ||
| out = np.zeros_like(first) + np.uint64(0x345678L) |
Contributor
There was a problem hiding this comment.
the L is not working in py3. (remove it and its ok).
Contributor
|
@mikegraham the collisions I found by hashing which is basically a cartesian product of 1000 x 1000. nothing special really, just a test case I am using. |
jreback
added
the
Algos
mikegraham
force-pushed
the
emulate_tuple
branch
2 times, most recently
from
7117b6b to
e52c872
Compare
mikegraham
force-pushed
the
emulate_tuple
branch
from
e52c872 to
187573b
Compare
Contributor
|
closing in favor of in #15224 thanks @mikegraham |
jreback
added a commit
that referenced
this pull request
Jan 27, 2017
closes #15227 Author: Jeff Reback <jeff@reback.net> Author: Mike Graham <mikegraham2gmail.com> Closes #15224 from jreback/mi_hash2 and squashes the following commits: 8b1d3f9 [Jeff Reback] not correctly hashing categorical in a MI 48a2402 [Jeff Reback] support for mixed type arrays 58f682d [Jeff Reback] memory optimization 0c13df7 [Mike Graham] Steal the algorithm used to combine hashes from tupleobject.c e8dd607 [Jeff Reback] add hash_tuples 44e9c7d [Mike Graham] wipSteal the algorithm used to combine hashes from tupleobject.c e507c4a [Jeff Reback] ENH: support MultiIndex and tuple hashing
AnkurDedania
pushed a commit
to AnkurDedania/pandas
that referenced
this pull request
Mar 21, 2017
closes pandas-dev#15227 Author: Jeff Reback <jeff@reback.net> Author: Mike Graham <mikegraham2gmail.com> Closes pandas-dev#15224 from jreback/mi_hash2 and squashes the following commits: 8b1d3f9 [Jeff Reback] not correctly hashing categorical in a MI 48a2402 [Jeff Reback] support for mixed type arrays 58f682d [Jeff Reback] memory optimization 0c13df7 [Mike Graham] Steal the algorithm used to combine hashes from tupleobject.c e8dd607 [Jeff Reback] add hash_tuples 44e9c7d [Mike Graham] wipSteal the algorithm used to combine hashes from tupleobject.c e507c4a [Jeff Reback] ENH: support MultiIndex and tuple hashing
2 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
closes #15224