Fastai2 and course (2020) important notice

fastai v2 will be released in the next few weeks, and it is not API-compatible with fastai v1 (it’s a from-scratch rewrite). It’s much easier to use, more powerful, and better documented than v1, and there’s even a book (624 pages!) about it. The book is also available for free as Jupyter notebooks. If you’re interested in experimenting with the pre-release version of fastai v2, you can get it here: .

To see updates to fastai v2, please see the following thread:

To get notified of changes to that thread, please selecting “Watching” from the menu at the bottom:

fastai v2 only works with the upcoming 2020 version of the course. It won’t work with any previous version. The 2020 version of the course will be available at the same time that fastai v2 is officially released. If you’re currently working through one of the existing courses, keep going! :slight_smile: The basic concepts you’re learning will be just as useful for fastai v2. There is no 2020 version of part 2 of the course recorded yet, and we don’t have a date for when that might happen.

The 2020 version of the course includes material covering both machine learning and deep learning. So there won’t be a separate “Introduction to Machine Learning” (although the old one will still be available).

fastai v1 will continue to be available, and we’ll continue to provide bug fixes (and accept pull requests for it). To pin your fastai version to v1 (i.e., to avoid it upgrading automatically to v2), run the following command (assuming you use conda):

 echo 'fastai 1.*' >> $CONDA_PREFIX/conda-meta/pinned

Then, when you’re ready to upgrade to v2, remove the $CONDA_PREFIX/conda-meta/pinned file.

The github repo for fastai v1 will shortly be renamed to fastai/fastai1, and the repo for v2 will shortly be renamed from fastai/fastai2 to fastai/fastai.

If you’re interested in getting involved in fastai2 development, or just watching my live coding sessions (which I do most days), connect to our Discord server, which is where I stream my live coding, and there’s some real-time fastai2 development discussion:

I’ll be moving all fastai development forum discussion into #fastai-users:fastai-dev. The forums are the best place to ask questions.


Is this equivalent to part1 from the last year? (including Machine Learning stuff)

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Roughly equivalent, yes.

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I have just started out with Part 1 of the course and I’m on Lesson 2. Would you recommend pausing for the 2020 version, or moving on?

I ask this question because if there are drastic changes in the APIs and workflow from fastai to fastai2, it might be beneficial to wait it out. From what I can gather, this is not the case, but it’d be great if someone can confirm this.


I’d suggest moving on.


One thing I have learned throughout my journey in fastai, is to pick a use case and do it exceptionally well. The version might matter, for sure; But applying the concepts and modules is barely done the same way., despite changes in syntax and modules denomination.
Can’t wait for Fastai2.


Hi - I assume the Part 1 will be a top-down approach, which is more like an intro to Deep Learning, like in 2018 and 2018. My question is: would any of the more ‘advanced’ stuff be covered anytime soon? For example, GANs, Transformers or Object Detectors? Or is there no plan in integrating those technologies to Fastai V2.


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Is part2 also covered in the book or is it separate content? Thanks.

From what Jeremy has said, a mix of both. The course covers the first half of the book, the second part would be the rest, with potentially room for other topics like object detection, etc (Jeremy’s words).

In regards to technologies, GAN’s are in there, with some object detection. That being said, those areas (and transformers) are a good place for smart folks to integrate it in (as it’s open source, so more than just Jeremy and Sylvain, they can only do so much :wink: ) For instance we have a HuggingFace port made already (currently an external library)

(Do note: by technologies I do not mean the course itself. It’s unknown, besides the rest of fastbook)