AI and ML

Cover photo by Conny Schneider https://unsplash.com/@choys_

ML Introduction

Welcome to my Machine Learning and AI notebook.

🧱 AI and ML Fundamentals

🗃️ Data Collection and Annotation

 

📚 LLMs

ML Best Practices

Machine learning is a complex and multifaceted activity that requires the combination of a number of success factors in order to work. In order to execute machine learning well, it is important to have a good understanding of the processes and variables that frequently come into play together. Here I document and lay out some of the best practices and ML processes that I have learned and continue to learn during my career.

A personal bugbear of mine is when people refer to machine learning as "an art rather than a science". It is true that machine learning involves random-seeming aspects that could be conflated with magic or wizardry. There are a lot of ways that poorly thought-through or executed machine learning projects can go wrong. However, there are well established protocols and principles that can guide a project towards success and we can execute projects in a risk-averse, incremental way allowing us to fail fast before a large amount of time and energy has been spent on a project.

Key Principles

Garbage In; Garbage Out

Machine learning is all about trying to infer statistical relationships between data. There are a lot of reasons why this might not work well which we will explore in depth. It's always important to remember that if you have bad data or a flawed hypothesis, your model is not going to perform well. Conversely, if your model is performing really well (perhaps "too good to be true" levels of well ) this can be a red flag that something is wrong with your data or your process which leads into...

Professional Pessimism

I love this phrase that I picked up during my career stint as a QA Engineer. If something appears to be too good to be true, it probably is. Always question your results and double check your working. Typically if a machine learning model is achieving high-90% in appropriate performance metrics, it is worth your time to investigate whether something weird is happening. You may have training data in your test set (i.e. your model got hold of the exam answer sheet) or your model may have found a short cut. For example, if all the positive examples of fractured ribs come from x-rays of women and all the negative examples come from x-rays of men then the model may have just learned to separate male and female anatomy rather than what a fractured rib looks like.

Keep it Simple, Stupid (KISS)

As tempting as it might be to want to use the latest and greatest ML models, always start with the simplest approach possible and disqualify these approaches based on sound theoretical rationale or empirical experimentation:

Keep Receipts

Machine Learning is usually an iterative process. As you move through this process it is important to understand where you came from and why at all times and to be able to refer back to earlier results and hypotheses. Furthermore, in a business setting, you will likely be asked questions about how work that you did days or weeks ago compares to your current iteration of thinking. 

Keeping receipts is about using simple tools (good note taking and ticket hygiene) in combination with more specific purpose-built AI and ML tooling to ensure that you can answer these questions at all times.

Deep Learning Best Practices

For deep learning I like to work with torch. My opinion on how torch code should be written aligns quite closely with this styleguide

Model Quantization

Deploying models that are performant (obviously statistically but in this context I primarily mean computationally) is challenging when you are working with large models such as BERT etc.

Quantization involves compressing model weights into smaller, more efficient representations. Weights are normally stored as 32 bit floating point numbers but they can be compressed into 8 bit integers with a very small amount of performance loss.

This article talks about how to do quantization effectively (mirror).

Quantization with Optimum and OpenVino

Openvino is an open source framework from Intel that provides quantization and x86 CPU support for torch and huggingface transformers.

SpaCy GPU

Set Up Environment

It's relatively easy to use SpaCy with a GPU these days.

First set up your conda environment and install cudatoolkit (use nvidia-smi to match versions of the tookit with the drivers):

Run nvidia-smi:

image.png

Create conda env:

conda create -n test python=3.8
conda activate test
conda install pytorch cudatoolkit=10.2 -c pytorch

Installing SpaCy

Now install spacy - depending on how you like to manage your python environments either carry on using conda for everything or switch to your preferred package manager at this point.

conda install -c conda-forge spacy cupy

or

pdm add 'spacy[cuda-autodetect]'

Download Models

Download a spacy transformer model to make use of your GPU/CUDA setup:

python -m spacy download en_core_web_trf

Using GPU

As soon as your code loads you should use theprefer_gpu()or require_gpu() functions to tell spacy to load cupy then load your model:

import spacy

spacy.require_gpu()

nlp = spacy.load('en_core_web_trf')

Now you can use the model to do some stuff

doc = nlp("My name is Wolfgang and I live in Berlin")

for ent in doc.ents:
    print(ent.text, ent.label_)

You can check that the GPU is actually in use with nvidia-smi:

image.png

Also if you try to use transformer models without a GPU it will hang for AGES and max out your CPUs - another tell that something's not quite right.

SpaCy CoRef

Spacy Coref is an experimental coreference resolution model in spacy

The project repository is here.

There is currently a hard dependency on the LDC OntoNotes dataset which makes it difficult to use without spending money. Hopefully they will release a pre-trained model soon

Core Scientific Concepts (CoreSC)

Core Scientific Concepts (CoreSC) is an annotation scheme used to delineate different parts of scientific discourse in a scientific paper.

There are 11 categories:

Classification Methods

References

Stratified Sampling in Pandas

df = pd.read_csv("path/to/data.csv")

df.groupby('Category', group_keys=False).apply(lambda x: x.sample(frac=0.1, random_state=42))

From Crowd Ratings to Predictive Models of Newsworthiness to Support Science Journalism

Authors:

Notes

Stable Diffusion

Web UI API

Run the web UI with:

./webui.sh --api

 

Example Python Script

import webuiapi


# create API client
api = webuiapi.WebUIApi()

# create API client with custom host, port
#api = webuiapi.WebUIApi(host='127.0.0.1', port=7860)

# create API client with custom host, port and https
#api = webuiapi.WebUIApi(host='webui.example.com', port=443, use_https=True)

# create API client with default sampler, steps.
#api = webuiapi.WebUIApi(sampler='Euler a', steps=20)

# optionally set username, password when --api-auth=username:password is set on webui.
# username, password are not protected and can be derived easily if the communication channel is not encrypted.
# you can also pass username, password to the WebUIApi constructor.

result1 = api.txt2img(width=512,height=768,
                    prompt="Morgan Freeman in star wars jedi robe",
                    negative_prompt="ugly, out of frame",
                    seed=1003,
                    styles=["anime"],
                    cfg_scale=7,
                    steps=30,
#                      sampler_index='DDIM',
#                      steps=30,
#                      enable_hr=True,
#                      hr_scale=2,
#                      hr_upscaler=webuiapi.HiResUpscaler.Latent,
#                      hr_second_pass_steps=20,
#                      hr_resize_x=1536,
#                      hr_resize_y=1024,
#                      denoising_strength=0.4,
                    alwayson_scripts = {
                        "ADetailer": {
                        "args": [
                            {
                            "ad_model": "face_yolov8n.pt"
                            }
                        ]
                        }
                    }
                    )

result1.image.save("out.png")


 

AI Causing Chaos

So much AI turns out to be low-waged people in a call center in the Global South pretending to be robots that Indian techies have a joke about it: “AI stands for ‘absent Indian’” - Cory Doctorow

I am collecting examples of AI fails by people who either deliberately or naively mislead about the capabilities of AI.

2024

2023

Tasks

Tasks within ML and NLP

Tasks

Question Answering

Approaches

Fine-Tuning Sentence-BERT for Question Answering

CapitalOne produced a tutorial (mirror) about using sentence-transformers for Question Answering.

Haystack

Haystack is an open source NLP framework for use cases involving large collections of documents. It could be used for searching and ranking type use cases and question answering type use cases.

Haystack works flexibly with existing document stores including DB systems and ElasticSearch.

Tasks

Coreference Resolution

Co-reference Resolution (CR) is the task of deciding whether two entity mentions refer to the same instance or not.

For example in:

Joe Biden appeared at the event at 8pm. The president was wearing a Louis Vuitton Tuxedo.

The objective is to identify that Joe Biden and The president are the same entity.

Coreference Detection is related to Relationship Extraction (RE) - in fact you could even say that CR is a special case of RE in the sense that we are interested in the special relationship between entity mentions when they both refer to the same entity.

In-Document Coreference Resolution

This is the "normal" CR case in which you're trying to resolve mentions of entities within the same document e.g. a single news article.

Approaches

Cross-Document Coreference Resolution

Cross-Document Coreference Resolution (CDCR) is when you try to link named entity references across multiple input documents. A use case might be identifying that a number of news articles do actually refer to the same person (e.g. "Joe Biden", "The President").

CDCR is challenging because there are so many possible entities and thus O(n2) comparisons to make between candidates.

Approaches

Tasks

Keyword Extraction

Graph-Based Keyword Extraction

Graph-based approaches like TextRank allows the extraction of keywords + phrases based on their centrality to the semantics of the other words in the document.

Tasks

Relationship Extraction

Relationship Extraction (RE) is a task that is related to Coreference Resolution but with a focus on identifying relationships between entities.

In the following example:

James, the CTO at Filament AI, lives in the South of England.

We want to identify the following relationships:

(James, isCTOof, Filament AI)
(James, livesIn, England)

Approaches

Tasks

Federated Learning

Tasks

Large Scale Multi-Label Learning

The Keras website has a tutorial on how to do multi-label learning with a large number of labels:

Machine Learning with Limited Data

Machine Learning with Limited Data

Pattern Exploitative Training

PET or Pattern Exploitative Training

image-1649077362304.png

@article{schick2020exploiting,
  title={Exploiting Cloze Questions for Few-Shot Text Classification and Natural Language Inference},
  author={Timo Schick and Hinrich Schütze},
  journal={Computing Research Repository},
  volume={arXiv:2001.07676},
  url={http://arxiv.org/abs/2001.07676},
  year={2020}
}

@article{schick2020small,
  title={It's Not Just Size That Matters: Small Language Models Are Also Few-Shot Learners},
  author={Timo Schick and Hinrich Schütze},
  journal={Computing Research Repository},
  volume={arXiv:2009.07118},
  url={http://arxiv.org/abs/2009.07118},
  year={2020}
}
Machine Learning with Limited Data

Learning with Limited Data

Good machine learning is heavily dependent on good data. A few more good data-points is likely to be worth billions of model parameters.

However, sometimes we need to train models when data is limited. There are a number of strategies that we can try.

Zero-Shot and Few-Shot Learning

 

In Context Learning (ICL)

Synthetic Data Generation and Augmentation

DeBERTa Zero Shot

The DeBERTa zero-shot model is an NLP zero-shot classifier trained by Moritz Laurer and made publically available on HuggingFace

Explainability and Model Analysis

Explainability and Model Analysis

Explainability

Explainability is a big challenge in machine learning.

I wrote a blog post about the ELI5 library and how it can be applied to NLP models.

Introducing ML customers to explainability early on can be a great way to build trust. A colleague suggests using Streamlit tools to allow customers to play with models and understand the contribution different features have had to a particular decision.

Explainability and Model Analysis

Model Confidence Scores

Many ML classification models can provide a confidence score which tells the user how confident the model is that it has made the correct choice.

The values of these confidence scores and what constitutes a "good" or "bad" score can vary a lot depending on the type and behaviour of the model. We often get asked why a particular model only ever seems to be 20% confident when a different model gives 99% confidence. Here's why that happens.

Confidence vs Certainty

Confidence and certainty are related but distinct concepts. We want models to be confident that they are correct (a high score is allocated to one of the labels and a low score allocated to the remaining labels) but also we want it to be certain it is correct (we want it to rely on features/cues that lead to the actual correct outcome).

Neural networks are known to often be over-confident in their results but still incorrect due to the way that modern deep learning learns. The paper On Calibration of Neural Networks dives into this further.

In order for us to be able to trust confidence scores, models must also be well calibrated.

Confidence in Random Forest Models

Random Forest Models are made up of an ensemble of decision tree models which are trained based on randomly selected sub-samples of the full training set - allowing the trees to learn different feature priorities based on the variance in the data that they are "assigned".

A single decision tree model cannot easily tell you how confident it is - the data is passed in and the algorithm traverses the branches in the tree until it reaches a decision. Within the random forest, confidence is calculated by assigning each tree a "vote" on the outcome class and then working out the distributions of votes across the possible outcome classes as a percentage.

In scikit-learn decision trees[ do have confidence scores](https://scikit-learn.org/stable/modules/generated/sklearn.tree.DecisionTreeClassifier.html#sklearn.tree.DecisionTreeClassifier.predict_proba) calculated as the proportion of each class that ended on a given leaf node during training

Say we train a random forest model containing 100 trees on a company sector/industry classification problem with 5 classes. In theory, some of the trees will learn to prioritise the most important features in the dataset. Likewise, we can assume that some of the trees will be trained on less representative sub-samples of the training data and will prioritise less discriminative features.

When we predict on an unseen data sample we might get an output like this:

We specialise in using AI to improve user experience for customers of high end grocery stores

35 Trees votes for "Consumer Goods"
25 Trees voted for "IT & Technology"
22 Trees voted for "Health & Beauty"
12 Trees voted for "Retail"
6 Trees voted for "Automotive Manufacturing"

I used 100 random trees in my model for easy maths, so we would say in this case that the model is 35% confident that this description is from a company in consumer goods.

Can We Calibrate Confidence in Random Forest Models?

Confidence calibration is a technique that allows us to more closely map the confidence of an ML model (via its decision function) onto the real life probability that a sample belongs to a particular class.

Confidence in Neural Networks

Neural classification models can have many different internal structures but tend to have a set of inputs that correspond to the feature vector of the task being learned (e.g. a sparse bag-of-words, a set of RGB pixel values or numerical sensor readings) and a set of outputs equal to the number of classes being predicted.

Activation functions in hidden layers can produce wildly different and un-normalised values depending on the inputs, random initialisations and what is learned (although we can use normalisation constraints in our learning to prevent individual weights from going too far).

The output of the model is therefore typically normalised using SoftMax which essentially takes a weighted average of the results - its a bit like saying "which output received a higher percentage of the overall signal propagated through the network?"

Can We Calibrate Confidence in Neural Networks?

Argilla

Argilla is a data annotation tool with an API that allows you to use external models to automatically suggest labels and carry out active learning.

Resources

- Argilla Few Shot Learning Tutorial - warning some of the code in this notebook is wrong