RoaringBitmap
data.int-map
| RoaringBitmap | data.int-map | |
|---|---|---|
| 24 | 3 | |
| 3,388 | 124 | |
| 0.8% | 0.0% | |
| 8.5 | 5.3 | |
| 10 days ago | 2 months ago | |
| Java | Java | |
| Apache License 2.0 | Eclipse Public License 1.0 |
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RoaringBitmap
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Iterating over Bit Sets Quickly
I was recently reading about Roaring https://roaringbitmap.org/ which is a highly optimized compressed bitset implementation. I reccomend reading about it if you are interested in this sort of thing. The talk at https://roaringbitmap.org/talks/ is especially good.
- Roaring Bitmaps
- Roaring bitmaps are compressed bitmaps, can be 100x faster
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What feature would you like to remove in C++26?
However, I would love compressed (not just packed) bitsets too, which is something different to me. I would make it another class with a similar interface, based on something like roaring. It doesn't need to be in the standard, but it would be nice if the API was a such that one could easily swap implementations.
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Jaccard Index
As an aside if you find yourself having to compute them on the fly, know that the Roaring Bitmaps libraries is the way to go [1]. The bitmaps are compressed, and can be streamed directly into SIMD computations (batching XORs and popcnts 256 bits wide!). The Jaccard index is just intersection_len / union_len [2] away
[1] https://roaringbitmap.org/
[2] https://roaringbitmap.readthedocs.io/en/latest/#roaringbitma...
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Looking for fast, space-efficient key-lookup
Use a two stage approach, with a bloom/cuckoo filter stored as a https://roaringbitmap.org/ in memory. Then a secondary key/value store on disk (bolt or anything else).
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BitSet Vs BigInteger
As an aside, if you're dealing with large bit sets, you might also want to evaluate Roaring Bitmaps.
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Negative Incentives in Academic Research
Sidetracking a bit the conversation. What a coincidence that the author (Lemire) is also represented on Today's #1 "Ask HN: What are some cool but obscure data structures you know about?" as he is the main contributor of RoaringBitmap https://github.com/RoaringBitmap/RoaringBitmap and one of the main authors of the data structure.
- Ask HN: What are some 'cool' but obscure data structures you know about?
- Roaring bitmaps: A better compressed bitset
data.int-map
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Using characters versus keyword as map keys
And if you're going to be using maps with integer keys in performance critical contexts, it may make sense to use https://github.com/clojure/data.int-map!
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Seeking: efficient CL bitsets.
Sure, definitely. It appears to me that this library uses a bespoke trie implementation. So it wouldn't be hard to clone, but indeed someone has to do it.
What are some alternatives?
HyperMinHash-java - Union, intersection, and set cardinality in loglog space
Primes - Prime Number Projects in C#/C++/Python
lucene - Apache Lucene open-source search software
cl-intset - A library for non-negative integer sets. It implements sets using bitsets.
CQEngine - Ultra-fast SQL-like queries on Java collections
Feign - Feign makes writing java http clients easier
maven-compiler-plugin - Apache Maven Compiler Plugin
alexandria - Full text search engine powering Alexandria.org - the open search engine.
Deeplearning4j - Suite of tools for deploying and training deep learning models using the JVM. Highlights include model import for keras, tensorflow, and onnx/pytorch, a modular and tiny c++ library for running math code and a java based math library on top of the core c++ library. Also includes samediff: a pytorch/tensorflow like library for running deep learning using automatic differentiation.
Flowable (V6) - A compact and highly efficient workflow and Business Process Management (BPM) platform for developers, system admins and business users.
clojure - The Clojure programming language