tree-flat
RoaringBitmap
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| tree-flat | RoaringBitmap | |
|---|---|---|
| 2 | 24 | |
| 25 | 3,372 | |
| - | 1.2% | |
| 1.9 | 8.5 | |
| 12 months ago | 6 days ago | |
| Rust | Java | |
| Apache License 2.0 | Apache License 2.0 |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
tree-flat
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Ask HN: What are some 'cool' but obscure data structures you know about?
I made https://github.com/mamcx/tree-flat as flattened stored tree in pre-order that allows for very fast iterations even for childs/parent queries. Is based on APL, so not that novel.
I also like a lot the relational model, is not that much represented so I making a language on top of it: https://tablam.org.
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What’s everyone working on this week (9/2022)?
Working in the flattest tree library for Rust (https://github.com/mamcx/tree-flat), inspired by the talk “High-performance Tree Wrangling, the APL Way” by Aaron Hsu.
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
What are some alternatives?
multiversion-concurrency-control - Implementation of multiversion concurrency control, Raft, Left Right concurrency Hashmaps and a multi consumer multi producer Ringbuffer, concurrent and parallel load-balanced loops, parallel actors implementation in Main.java, Actor2.java and a parallel interpreter
HyperMinHash-java - Union, intersection, and set cardinality in loglog space
indicatif - A command line progress reporting library for Rust
lucene - Apache Lucene open-source search software
atomic-server - An open source headless CMS / real-time database. Powerful table editor, full-text search, and SDKs for JS / React / Svelte.
CQEngine - Ultra-fast SQL-like queries on Java collections
conserve - 🌲 Robust file backup tool in Rust
Primes - Prime Number Projects in C#/C++/Python
ann-benchmarks - Benchmarks of approximate nearest neighbor libraries in Python
Feign - Feign makes writing java http clients easier
entt - Gaming meets modern C++ - a fast and reliable entity component system (ECS) and much more
maven-compiler-plugin - Apache Maven Compiler Plugin