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Comment by rlayton2 | Hacker News Reader

Note that the top level summary shows it is 10x faster than Spacey, which is a more impressive achievement than being 10x faster than NLTK (it is 20x faster).

NLTK is designed for learning, not for production systems, speed or efficiency. The code is often the most straight-forward way to implement an algorithm, especially to read the code later.

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I have been experimenting with tokenization in Rust in https://github.com/rth/vtext, mostly relying on Unicode segmentation with a few custom rules for tokenization. The obtained performance was also around 10x faster than spacy for comparable precision (see benchmarks section of the readme).

To further your point, NLTK is written in pure Python whereas the backend for spaCy, thinc, is written in C/C++/Python. Really no comparison here.

Anyone familiar enough with this library to explain how they've achieved such impressive performance? Otherwise, may dig into it for a blog post when I have time.

There are deterministic finite state machines underneath implemented in lean C++. These automata allow to implement operations with strings optimally or close to that. In the readme file there is a link to how to recompile linguistic resources, if you look inside the makefile that is used for resource compilation you will the steps.

Do you use any kind of library or typical design pattern for your FSM implementation? When I've used them, I typically always go back to very C-like code (enum for the states, a state variable, and a big switch statement inside a loop).

We don't represent automata as a code, that leads to compiler errors etc., we represent them as graphs, just as data.

Inside the code we use: state --> int set of states --> sorted / unique'd array of int's input symbol --> int output symbol --> int transition function is abstracted out behind an interface and implemented differently based on whether automaton is read-only or changeable and based on the state etc.

I'm going to have to think about that a bit. Maybe I'm missing the point, but it sounds like an interpreter. Thanks for posting the code. This feels like something I need to understand.

Thanks - will dive in and start checking things out.

What is lean C++?

I think he just means efficient C++ programming.

#define WIN32_LEAN_AND_MEAN

Maybe ?

One advantage is the core appears to be written in C/C++. NLTK is python and SpaCy is a lot of C/C++ with a significant amount of python.

I’ll have to dig in further, but I suspect there’s a lot of optimization for the task at hand here. SpaCy and NLTK tries to be much more general for NLP.

I was more so referring to spacy, where (IIRC) a lot of the lower-level tokenization & parsing is written in Cython, so (I assume) the simple fact that Bling is written in C++ wouldn't explain the huge performance gains.

There’s still a good amount of overhead in Cython portions of code unless there are no python objects or GIL involved, and then there’s still overhead communicating between C and Python worlds.

That’s part of why I stopped writing Cython and just use pybind11.

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