GPT-2 is a transformers model pre-trained on a very large corpus of English data in a self-supervised fashion. This means it was pre-trained on the raw texts only, with no humans labeling them in any way (which is why it can use lots of publicly available data) with an automatic process to generate inputs and labels from those texts. More precisely, it was trained to guess the next word in sentences.

More precisely, inputs are sequences of continuous text of a certain length and the targets are the same sequence, shifting one token (word or piece of word) to the right. The model uses a masking mechanism to make sure the predictions for the token i only use the inputs from 1 to i but not the future tokens.

This way, the model learns an inner representation of the English language that can then be used to extract features useful for downstream tasks. The model is best at what it was trained for, however, which is generating texts from a prompt.

To use this model

python

>>> from transformers import AutoTokenizer, AutoModelForCausalLM
>>> model_name = "Sharathhebbar24/chat_gpt2"
>>> model = AutoModelForCausalLM.from_pretrained(model_name)
>>> tokenizer = AutoTokenizer.from_pretrained(model_name)
>>> def generate_text(prompt):
>>>  inputs = tokenizer.encode(prompt, return_tensors='pt')
>>>  outputs = model.generate(inputs, max_length=64, pad_token_id=tokenizer.eos_token_id)
>>>  generated = tokenizer.decode(outputs[0], skip_special_tokens=True)
>>>  return generated[:generated.rfind(".")+1]
>>> prompt = """
>>> user: what are you?
>>> assistant: I am a Chatbot intended to give a python program
>>> user: hmm,  can you write a python program to print Hii Heloo
>>> assistant: Sure Here is a python code.\n print("Hii Heloo")
>>> user: Can you write a Linear search program in python
>>> """
>>> res = generate_text(prompt)
>>> res

Open LLM Leaderboard Evaluation Results

Detailed results can be found here

Metric	Value
Avg.	27.99
AI2 Reasoning Challenge (25-Shot)	23.04
HellaSwag (10-Shot)	30.76
MMLU (5-Shot)	24.39
TruthfulQA (0-shot)	39.81
Winogrande (5-shot)	49.96
GSM8k (5-shot)	0.00