Sentiment Analysis with OpenVINO™

This tutorial is also available as a Jupyter notebook that can be cloned directly from GitHub. See the installation guide for instructions to run this tutorial locally on Windows, Linux or macOS. To run without installing anything, click the launch binder button.

Binder Github

Sentiment analysis is the use of natural language processing, text analysis, computational linguistics, and biometrics to systematically identify, extract, quantify, and study affective states and subjective information. This notebook demonstrates how to convert and run a sequence classification model using OpenVINO.


from transformers import DistilBertForSequenceClassification, AutoTokenizer
import openvino.runtime as ov
import warnings
from pathlib import Path
import numpy as np
import time
import torch

Initializing the Model

We will use the transformer-based distilbert-base-uncased-finetuned-sst-2-english model from Hugging Face.

checkpoint = "distilbert-base-uncased-finetuned-sst-2-english"
model = DistilBertForSequenceClassification.from_pretrained(

Initializing the Tokenizer

Text Preprocessing cleans the text-based input data so it can be fed into the model. Tokenization splits paragraphs and sentences into smaller units that can be more easily assigned meaning. It involves cleaning the data and assigning tokens or IDs to the words, so they are represented in a vector space where similar words have similar vectors. This helps the model understand the context of a sentence. Here, we will use AutoTokenizer - a pre-trained tokenizer from Hugging Face: .

tokenizer = AutoTokenizer.from_pretrained(

Convert to ONNX

ONNX is an open format built to represent machine learning models. ONNX defines a common set of operators - the building blocks of machine learning and deep learning models - and a common file format to enable AI developers to use models with a variety of frameworks, tools, runtimes, and compilers. We need to convert the model from PyTorch to ONNX. In order to perform the operation, we use a function torch.onnx.export to convert a Hugging Face model to its respective ONNX format.

onnx_model = "distilbert.onnx"
MODEL_DIR = "model/"
onnx_model_path = Path(MODEL_DIR) / onnx_model
dummy_model_input = tokenizer("This is a sample", return_tensors="pt")
    input_names=['input_ids', 'attention_mask'],
    dynamic_axes={'input_ids': {0: 'batch_size', 1: 'sequence'},
                  'attention_mask': {0: 'batch_size', 1: 'sequence'},
                  'logits': {0: 'batch_size', 1: 'sequence'}},
/opt/home/k8sworker/cibuilds/ov-notebook/OVNotebookOps-408/.workspace/scm/ov-notebook/.venv/lib/python3.8/site-packages/transformers/models/distilbert/ TracerWarning: torch.tensor results are registered as constants in the trace. You can safely ignore this warning if you use this function to create tensors out of constant variables that would be the same every time you call this function. In any other case, this might cause the trace to be incorrect.
  mask, torch.tensor(torch.finfo(scores.dtype).min)

Model Optimizer

Model Optimizer is a cross-platform command-line tool that facilitates the transition between training and deployment environments, performs static model analysis, and adjusts deep learning models for optimal execution on end-point target devices.

optimizer_command = f'mo \
    --input_model {onnx_model} \
    --output_dir {MODEL_DIR} \
    --model_name {checkpoint} \
    --input input_ids,attention_mask \
    --input_shape "[1,128],[1,128]"'
! $optimizer_command
huggingface/tokenizers: The current process just got forked, after parallelism has already been used. Disabling parallelism to avoid deadlocks...
To disable this warning, you can either:
    - Avoid using tokenizers before the fork if possible
    - Explicitly set the environment variable TOKENIZERS_PARALLELISM=(true | false)
Check for a new version of Intel(R) Distribution of OpenVINO(TM) toolkit here or on
[ INFO ] The model was converted to IR v11, the latest model format that corresponds to the source DL framework input/output format. While IR v11 is backwards compatible with OpenVINO Inference Engine API v1.0, please use API v2.0 (as of 2022.1) to take advantage of the latest improvements in IR v11.
Find more information about API v2.0 and IR v11 at
[ SUCCESS ] Generated IR version 11 model.
[ SUCCESS ] XML file: /opt/home/k8sworker/cibuilds/ov-notebook/OVNotebookOps-408/.workspace/scm/ov-notebook/notebooks/229-distilbert-sequence-classification/model/distilbert-base-uncased-finetuned-sst-2-english.xml
[ SUCCESS ] BIN file: /opt/home/k8sworker/cibuilds/ov-notebook/OVNotebookOps-408/.workspace/scm/ov-notebook/notebooks/229-distilbert-sequence-classification/model/distilbert-base-uncased-finetuned-sst-2-english.bin

OpenVINO™ Runtime uses the Infer Request mechanism which enables running models on different devices in asynchronous or synchronous manners. The model graph is sent as an argument to the OpenVINO API and an inference request is created. The default inference mode is AUTO but it can be changed according to requirements and hardware available. You can explore the different inference modes and their usage in documentation.

core = ov.Core()
ir_model_xml = str((Path(MODEL_DIR) / checkpoint).with_suffix(".xml"))
compiled_model = core.compile_model(ir_model_xml)
infer_request = compiled_model.create_infer_request()
def softmax(x):
    Defining a softmax function to extract
    the prediction from the output of the IR format
    Parameters: Logits array
    Returns: Probabilities

    e_x = np.exp(x - np.max(x))
    return e_x / e_x.sum()


def infer(input_text):
    Creating a generic inference function
    to read the input and infer the result
    into 2 classes: Positive or Negative.
    Parameters: Text to be processed
    Returns: Label: Positive or Negative.

    input_text = tokenizer(
    inputs = dict(input_text)
    label = {0: "NEGATIVE", 1: "POSITIVE"}
    result = infer_request.infer(inputs=inputs)
    for i in result.values():
        probability = np.argmax(softmax(i))
    return label[probability]

For a single input sentence

input_text = "I had a wonderful day"
start_time = time.perf_counter()
result = infer(input_text)
end_time = time.perf_counter()
total_time = end_time - start_time
print("Label: ", result)
print("Total Time: ", "%.2f" % total_time, " seconds")
Total Time:  0.02  seconds

Read from a text file

start_time = time.perf_counter()
with open("../data/text/food_reviews.txt", "r") as f:
    input_text = f.readlines()
    for lines in input_text:
        print("User Input: ", lines)
        result = infer(lines)
        print("Label: ", result, "\n")
end_time = time.perf_counter()
total_time = end_time - start_time
print("Total Time: ", "%.2f" % total_time, " seconds")
User Input:  The food was horrible.


User Input:  We went because the restaurant had good reviews.

Total Time:  0.03  seconds