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Text Prediction with OpenVINO™
==============================
This notebook shows text prediction with OpenVINO. This notebook can
work in two different modes, Text Generation and Conversation, which the
user can select via selecting the model in the Model Selection Section.
We use three models
`GPT-2 <https://d4mucfpksywv.cloudfront.net/better-language-models/language_models_are_unsupervised_multitask_learners.pdf>`__,
`GPT-Neo <https://zenodo.org/record/5297715#.ZAmpsXZBztU>`__, and
`PersonaGPT <https://arxiv.org/abs/2110.12949v1>`__, which are a part of
the Generative Pre-trained Transformer (GPT) family. GPT-2 and GPT-Neo
can be used for text generation, whereas PersonaGPT is trained for the
downstream task of conversation.
GPT-2 and GPT-Neo are pre-trained on a large corpus of English text
using unsupervised training. They both display a broad set of
capabilities, including the ability to generate conditional synthetic
text samples of unprecedented quality, where we prime the model with an
input and have it generate a lengthy continuation.
More Details about the models are provided on their huggingface cards:
- `GPT-2 <https://huggingface.co/gpt2>`__
- `GPT-Neo <https://huggingface.co/EleutherAI/gpt-neo-125M>`__
PersonaGPT is an open-domain conversational agent that can decode
*personalized* and *controlled* responses based on user input. It is
built on the pretrained
`DialoGPT-medium <https://github.com/microsoft/DialoGPT>`__ model,
following the `GPT-2 <https://github.com/openai/gpt-2>`__ architecture.
PersonaGPT is fine-tuned on the
`Persona-Chat <https://arxiv.org/pdf/1801.07243>`__ dataset. The model
is available from
`HuggingFace <https://huggingface.co/af1tang/personaGPT>`__. PersonaGPT
displays a broad set of capabilities, including the ability to take on
personas, where we prime the model with few facts and have it generate
based upon that, it can also be used for creating a chatbot on a
knowledge base.
The following image illustrates the complete demo pipeline used for text
generation:
.. figure:: https://user-images.githubusercontent.com/91228207/163990722-d2713ede-921e-4594-8b00-8b5c1a4d73b5.jpeg
:alt: image2
image2
This is a demonstration in which the user can type the beginning of the
text and the network will generate a further. This procedure can be
repeated as many times as the user desires.
For Text Generation, The model input is tokenized text, which serves as
the initial condition for text generation. Then, logits from the models
inference results are obtained, and the token with the highest
probability is selected using the top-k sampling strategy and joined to
the input sequence. This procedure repeats until the end of the sequence
token is received or the specified maximum length is reached. After
that, tokenized IDs are decoded to text.
The following image illustrates the demo pipeline for conversation:
.. figure:: https://user-images.githubusercontent.com/95569637/226101538-e204aebd-a34f-4c8b-b90c-5363ba41c080.jpeg
:alt: image2
image2
For Conversation, User Input is tokenized with eos_token concatenated in
the end. Then, the text gets generated as detailed above. The Generated
response is added to the history with the eos_token at the end.
Additional user input is added to the history, and the sequence is
passed back into the model.
Model Selection
---------------
Select the Model to be used for text generation, GPT-2 and GPT-Neo are
used for text generation wheras PersonaGPT is used for Conversation.
.. code:: ipython3
# Install Gradio for Interactive Inference and other requirements
!pip install -q 'openvino-dev>=2023.0.0'
!pip install -q gradio
!pip install -q transformers[torch] onnx
.. parsed-literal::
ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
pytorch-lightning 1.6.5 requires protobuf<=3.20.1, but you have protobuf 4.23.4 which is incompatible.
.. code:: ipython3
from gradio import Blocks, Chatbot, Textbox, Row, Column
import ipywidgets as widgets
style = {'description_width': 'initial'}
model_name = widgets.Select(
options=['PersonaGPT (Converastional)', 'GPT-2', 'GPT-Neo'],
value='PersonaGPT (Converastional)',
description='Select Model:',
disabled=False
)
widgets.VBox([model_name])
.. parsed-literal::
VBox(children=(Select(description='Select Model:', options=('PersonaGPT (Converastional)', 'GPT-2', 'GPT-Neo')…
Load Model
----------
Download the Selected Model and Tokenizer from Huggingface
.. code:: ipython3
from transformers import GPTNeoForCausalLM, GPT2TokenizerFast, GPT2Tokenizer, GPT2LMHeadModel
if model_name.value == "PersonaGPT (Converastional)":
pt_model = GPT2LMHeadModel.from_pretrained('af1tang/personaGPT')
tokenizer = GPT2Tokenizer.from_pretrained('af1tang/personaGPT')
elif model_name.value == 'GPT-2':
pt_model = GPT2LMHeadModel.from_pretrained('gpt2')
tokenizer = GPT2Tokenizer.from_pretrained('gpt2')
elif model_name.value == 'GPT-Neo':
pt_model = GPTNeoForCausalLM.from_pretrained('EleutherAI/gpt-neo-125M')
tokenizer = GPT2TokenizerFast.from_pretrained('EleutherAI/gpt-neo-125M')
Convert Pytorch Model to OpenVINO IR
------------------------------------
.. figure:: https://user-images.githubusercontent.com/29454499/211261803-784d4791-15cb-4aea-8795-0969dfbb8291.png
:alt: conversion_pipeline
conversion_pipeline
For starting work with GPT-Neo model using OpenVINO, model should be
converted to OpenVINO Intermediate Represenation (IR) format.
HuggingFace provides gpt-neo model in PyTorch format, which supported in
OpenVINO via conversion to ONNX. We use HuggingFace transformers
librarys oonx module to export model to ONNX.
``transformers.onnx.export`` accepts preprocessing function for input
sample generation (tokenizer in our case),an instance of model, ONNX
export configuration, ONNX opset version for export and output path.
More information about transformers export to ONNX can be found in
HuggingFace
`documentation <https://huggingface.co/docs/transformers/serialization>`__.
While ONNX models are directly supported by OpenVINO runtime, it can be
useful to convert them to IR format to take advantage of OpenVINO
optimization tools and features. ``mo.convert_model`` python function
can be used for converting model using `OpenVINO Model
Optimizer <https://docs.openvino.ai/2023.0/openvino_docs_MO_DG_Python_API.html>`__.
The function returns instance of OpenVINO Model class, which is ready to
use in Python interface but can also be serialized to OpenVINO IR format
for future execution using ``openvino.runtime.serialize``. In our case,
``compress_to_fp16`` parameter is enabled for compression model weights
to fp16 precision and also specified dynamic input shapes with possible
shape range (from 1 token to maximum length defined in our processing
function) for optimization of memory consumption.
.. code:: ipython3
from pathlib import Path
from openvino.runtime import serialize
from openvino.tools import mo
from transformers.onnx import export, FeaturesManager
# define path for saving onnx model
onnx_path = Path("model/text_generator.onnx")
onnx_path.parent.mkdir(exist_ok=True)
# define path for saving openvino model
model_path = onnx_path.with_suffix(".xml")
# get model onnx config function for output feature format casual-lm
model_kind, model_onnx_config = FeaturesManager.check_supported_model_or_raise(pt_model, feature='causal-lm')
# fill onnx config based on pytorch model config
onnx_config = model_onnx_config(pt_model.config)
# convert model to onnx
onnx_inputs, onnx_outputs = export(preprocessor=tokenizer,model=pt_model,config=onnx_config,opset=onnx_config.default_onnx_opset,output=onnx_path)
# convert model to openvino
if model_name.value == "PersonaGPT (Converastional)":
ov_model = mo.convert_model(onnx_path, compress_to_fp16=True, input="input_ids[1,1..1000],attention_mask[1,1..1000]")
else:
ov_model = mo.convert_model(onnx_path, compress_to_fp16=True, input="input_ids[1,1..128],attention_mask[1,1..128]")
# serialize openvino model
serialize(ov_model, str(model_path))
.. parsed-literal::
/opt/home/k8sworker/ci-ai/cibuilds/ov-notebook/OVNotebookOps-448/.workspace/scm/ov-notebook/.venv/lib/python3.8/site-packages/transformers/models/gpt2/modeling_gpt2.py:810: TracerWarning: Converting a tensor to a Python boolean might cause the trace to be incorrect. We can't record the data flow of Python values, so this value will be treated as a constant in the future. This means that the trace might not generalize to other inputs!
if batch_size <= 0:
Load the model
~~~~~~~~~~~~~~
We start by building an OpenVINO Core object. Then we read the network
architecture and model weights from the .xml and .bin files,
respectively. Finally, we compile the model for the desired device.
Because we use the dynamic shapes feature, which is only available on
CPU, we must use ``CPU`` for the device. Dynamic shapes support on GPU
is coming soon.
Since the text recognition model has a dynamic input shape, you cannot
directly switch device to ``GPU`` for inference on integrated or
discrete Intel GPUs. In order to run inference on iGPU or dGPU with this
model, you will need to resize the inputs to this model to use a fixed
size and then try running the inference on ``GPU`` device.
.. code:: ipython3
from openvino.runtime import Core
# initialize openvino core
core = Core()
# read the model and corresponding weights from file
model = core.read_model(model_path)
# compile the model for CPU devices
compiled_model = core.compile_model(model=model, device_name="CPU")
# get output tensors
output_key = compiled_model.output(0)
Input keys are the names of the input nodes and output keys contain
names of the output nodes of the network. In the case of GPT-Neo, we
have ``batch size`` and ``sequence length`` as inputs and
``batch size``, ``sequence length`` and ``vocab size`` as outputs.
Pre-Processing
--------------
NLP models often take a list of tokens as a standard input. A token is a
word or a part of a word mapped to an integer. To provide the proper
input, we use a vocabulary file to handle the mapping. So first lets
load the vocabulary file.
Define tokenization
-------------------
.. code:: ipython3
from typing import List, Tuple
# this function converts text to tokens
def tokenize(text: str) -> Tuple[List[int], List[int]]:
"""
tokenize input text using GPT2 tokenizer
Parameters:
text, str - input text
Returns:
input_ids - np.array with input token ids
attention_mask - np.array with 0 in place, where should be padding and 1 for places where original tokens are located, represents attention mask for model
"""
inputs = tokenizer(text, return_tensors="np")
return inputs["input_ids"], inputs["attention_mask"]
``eos_token`` is special token, which means that generation is finished.
We store the index of this token in order to use this index as padding
at later stage.
.. code:: ipython3
eos_token_id = tokenizer.eos_token_id
eos_token = tokenizer.decode(eos_token_id)
Define Softmax layer
~~~~~~~~~~~~~~~~~~~~
A softmax function is used to convert top-k logits into a probability
distribution.
.. code:: ipython3
import numpy as np
def softmax(x : np.array) -> np.array:
e_x = np.exp(x - np.max(x, axis=-1, keepdims=True))
summation = e_x.sum(axis=-1, keepdims=True)
return e_x / summation
Set the minimum sequence length
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the minimum sequence length is not reached, the following code will
reduce the probability of the ``eos`` token occurring. This continues
the process of generating the next words.
.. code:: ipython3
def process_logits(cur_length: int, scores: np.array, eos_token_id : int, min_length : int = 0) -> np.array:
"""
Reduce probability for padded indices.
Parameters:
cur_length: Current length of input sequence.
scores: Model output logits.
eos_token_id: Index of end of string token in model vocab.
min_length: Minimum length for applying postprocessing.
Returns:
Processed logits with reduced probability for padded indices.
"""
if cur_length < min_length:
scores[:, eos_token_id] = -float("inf")
return scores
Top-K sampling
~~~~~~~~~~~~~~
In Top-K sampling, we filter the K most likely next words and
redistribute the probability mass among only those K next words.
.. code:: ipython3
def get_top_k_logits(scores : np.array, top_k : int) -> np.array:
"""
Perform top-k sampling on the logits scores.
Parameters:
scores: np.array, model output logits.
top_k: int, number of elements with the highest probability to select.
Returns:
np.array, shape (batch_size, sequence_length, vocab_size),
filtered logits scores where only the top-k elements with the highest
probability are kept and the rest are replaced with -inf
"""
filter_value = -float("inf")
top_k = min(max(top_k, 1), scores.shape[-1])
top_k_scores = -np.sort(-scores)[:, :top_k]
indices_to_remove = scores < np.min(top_k_scores)
filtred_scores = np.ma.array(scores, mask=indices_to_remove,
fill_value=filter_value).filled()
return filtred_scores
Main Processing Function
~~~~~~~~~~~~~~~~~~~~~~~~
Generating the predicted sequence.
.. code:: ipython3
def generate_sequence(input_ids : List[int], attention_mask : List[int], max_sequence_length : int = 128,
eos_token_id : int = eos_token_id, dynamic_shapes : bool = True) -> List[int]:
"""
Generates a sequence of tokens using a pre-trained language model.
Parameters:
input_ids: np.array, tokenized input ids for model
attention_mask: np.array, attention mask for model
max_sequence_length: int, maximum sequence length for stopping iteration
eos_token_id: int, index of the end-of-sequence token in the model's vocabulary
dynamic_shapes: bool, whether to use dynamic shapes for inference or pad model input to max_sequence_length
Returns:
np.array, the predicted sequence of token ids
"""
while True:
cur_input_len = len(input_ids[0])
if not dynamic_shapes:
pad_len = max_sequence_length - cur_input_len
model_input_ids = np.concatenate((input_ids, [[eos_token_id] * pad_len]), axis=-1)
model_input_attention_mask = np.concatenate((attention_mask, [[0] * pad_len]), axis=-1)
else:
model_input_ids = input_ids
model_input_attention_mask = attention_mask
outputs = compiled_model({"input_ids": model_input_ids, "attention_mask": model_input_attention_mask})[output_key]
next_token_logits = outputs[:, cur_input_len - 1, :]
# pre-process distribution
next_token_scores = process_logits(cur_input_len,
next_token_logits, eos_token_id)
top_k = 20
next_token_scores = get_top_k_logits(next_token_scores, top_k)
# get next token id
probs = softmax(next_token_scores)
next_tokens = np.random.choice(probs.shape[-1], 1,
p=probs[0], replace=True)
# break the loop if max length or end of text token is reached
if cur_input_len == max_sequence_length or next_tokens[0] == eos_token_id:
break
else:
input_ids = np.concatenate((input_ids, [next_tokens]), axis=-1)
attention_mask = np.concatenate((attention_mask, [[1] * len(next_tokens)]), axis=-1)
return input_ids
Inference with GPT-Neo/GPT-2
----------------------------
The ``text`` variable below is the input used to generate a predicted
sequence.
.. code:: ipython3
import time
if not model_name.value == "PersonaGPT (Converastional)":
text = "Deep learning is a type of machine learning that uses neural networks"
input_ids, attention_mask = tokenize(text)
start = time.perf_counter()
output_ids = generate_sequence(input_ids, attention_mask)
end = time.perf_counter()
output_text = " "
# Convert IDs to words and make the sentence from it
for i in output_ids[0]:
output_text += tokenizer.batch_decode([i])[0]
print(f"Generation took {end - start:.3f} s")
print(f"Input Text: {text}")
print()
print(f"{model_name.value}: {output_text}")
else:
print("Selected Model is PersonaGPT. Please select GPT-Neo or GPT-2 in the first cell to generate text sequences")
.. parsed-literal::
Selected Model is PersonaGPT. Please select GPT-Neo or GPT-2 in the first cell to generate text sequences
Conversation with PersonaGPT using OpenVINO™
============================================
User Input is tokenized with eos_token concatenated in the end. Model
input is tokenized text, which serves as initial condition for
generation, then logits from model inference result should be obtained
and token with the highest probability is selected using top-k sampling
strategy and joined to input sequence. The procedure repeats until end
of sequence token will be recived or specified maximum length is
reached. After that, decoding token ids to text using tokenized should
be applied.
The Generated response is added to the history with the eos_token at the
end. Further User Input is added to it and agin passed into the model.
Converse Function
-----------------
Wrapper on generate sequence function to support conversation
.. code:: ipython3
def converse(input: str, history: List[int], eos_token: str = eos_token,
eos_token_id: int = eos_token_id) -> Tuple[str, List[int]]:
"""
Converse with the Model.
Parameters:
input: Text input given by the User
history: Chat History, ids of tokens of chat occured so far
eos_token: end of sequence string
eos_token_id: end of sequence index from vocab
Returns:
response: Text Response generated by the model
history: Chat History, Ids of the tokens of chat occured so far,including the tokens of generated response
"""
# Get Input Ids of the User Input
new_user_input_ids, _ = tokenize(input + eos_token)
# append the new user input tokens to the chat history, if history exists
if len(history) == 0:
bot_input_ids = new_user_input_ids
else:
bot_input_ids = np.concatenate([history, new_user_input_ids[0]])
bot_input_ids = np.expand_dims(bot_input_ids, axis=0)
# Create Attention Mask
bot_attention_mask = np.ones_like(bot_input_ids)
# Generate Response from the model
history = generate_sequence(bot_input_ids, bot_attention_mask, max_sequence_length=1000)
# Add the eos_token to mark end of sequence
history = np.append(history[0], eos_token_id)
# convert the tokens to text, and then split the responses into lines and retrieve the response from the Model
response = ''.join(tokenizer.batch_decode(history)).split(eos_token)[-2]
return response, history
Conversation Class
------------------
.. code:: ipython3
class Conversation:
def __init__(self):
# Initialize Empty History
self.history = []
self.messages = []
def chat(self, input_text):
"""
Wrapper Over Converse Function.
Parameters:
input_text: Text input given by the User
Returns:
response: Text Response generated by the model
"""
response, self.history = converse(input_text, self.history)
self.messages.append(f"Person: {input_text}")
self.messages.append(f"PersonaGPT: {response}")
return response
Conversation with PersonaGPT
----------------------------
This notebook provides two styles of inference, Plain and Interactive.
The style of inference can be selected in the next cell.
.. code:: ipython3
style = {'description_width': 'initial'}
interactive_mode = widgets.Select(
options=['Plain', 'Interactive'],
value='Plain',
description='Inference Style:',
disabled=False
)
widgets.VBox([interactive_mode])
.. parsed-literal::
VBox(children=(Select(description='Inference Style:', options=('Plain', 'Interactive'), value='Plain'),))
.. code:: ipython3
if model_name.value == "PersonaGPT (Converastional)":
if interactive_mode.value == 'Plain':
conversation = Conversation()
user_prompt = None
pre_written_prompts = ["Hi,How are you?", "What are you doing?", "I like to dance,do you?", "Can you recommend me some books?"]
# Number of responses generated by model
n_prompts = 10
for i in range(n_prompts):
# Uncomment for taking User Input
# user_prompt = input()
if not user_prompt:
user_prompt = pre_written_prompts[i % len(pre_written_prompts)]
conversation.chat(user_prompt)
print(conversation.messages[-2])
print(conversation.messages[-1])
user_prompt = None
else:
def add_text(history, text):
history = history + [(text, None)]
return history, ""
conversation = Conversation()
def bot(history):
conversation.chat(history[-1][0])
response = conversation.messages[-1]
history[-1][1] = response
return history
with Blocks() as demo:
chatbot = Chatbot([], elem_id="chatbot").style()
with Row():
with Column():
txt = Textbox(
show_label=False,
placeholder="Enter text and press enter, or upload an image",
).style(container=False)
txt.submit(add_text, [chatbot, txt], [chatbot, txt]).then(
bot, chatbot, chatbot
)
demo.launch()
else:
print("Selected Model is not PersonaGPT, Please select PersonaGPT in the first cell to have a conversation")
.. parsed-literal::
Person: Hi,How are you?
PersonaGPT: good, how are you doing?
Person: What are you doing?
PersonaGPT: i'm good thanks what are you up too
Person: I like to dance,do you?
PersonaGPT: i like to read books
Person: Can you recommend me some books?
PersonaGPT: yes i can i like books about dance
Person: Hi,How are you?
PersonaGPT: i am good thanks for asking
Person: What are you doing?
PersonaGPT: i'm just sitting at home reading
Person: I like to dance,do you?
PersonaGPT: no but i love reading
Person: Can you recommend me some books?
PersonaGPT: yes i like to read too
Person: Hi,How are you?
PersonaGPT: good. do you like to cook?
Person: What are you doing?
PersonaGPT: i'm cooking right now.