backend/inference.py

import gzip
import json
from collections import Counter

import pandas as pd
import numpy as np
import jax.numpy as jnp
import tqdm

from sentence_transformers import util
from typing import List, Union
import torch

from backend.utils import load_model, filter_questions, load_embeddings
from sklearn.manifold import TSNE

def cos_sim(a, b):
    return jnp.matmul(a, jnp.transpose(b)) / (jnp.linalg.norm(a) * jnp.linalg.norm(b))


# We get similarity between embeddings.
def text_similarity(anchor: str, inputs: List[str], model_name: str, model_dict: dict):
    print(model_name)
    model = load_model(model_name, model_dict)

    # Creating embeddings
    if hasattr(model, 'encode'):
        anchor_emb = model.encode(anchor)[None, :]
        inputs_emb = model.encode(inputs)
    else:
        assert len(model) == 2
        anchor_emb = model[0].encode(anchor)[None, :]
        inputs_emb = model[1].encode(inputs)

    # Obtaining similarity
    similarity = list(jnp.squeeze(cos_sim(anchor_emb, inputs_emb)))

    # Returning a Pandas' dataframe
    d = {'inputs': inputs,
         'score': [round(similarity[i], 3) for i in range(len(similarity))]}
    df = pd.DataFrame(d, columns=['inputs', 'score'])

    return df


# Search
def text_search(anchor: str, n_answers: int, model_name: str, model_dict: dict):
    # Proceeding with model
    print(model_name)
    assert model_name == "distilbert_qa"
    model = load_model(model_name, model_dict)

    # Creating embeddings
    query_emb = model.encode(anchor, convert_to_tensor=True)[None, :]

    print("loading embeddings")
    corpus_emb = load_embeddings()

    # Getting hits
    hits = util.semantic_search(query_emb, corpus_emb, score_function=util.dot_score, top_k=n_answers)[0]

    filtered_posts = filter_questions("python")
    print(f"{len(filtered_posts)} posts found with tag: python")

    hits_titles = []
    hits_scores = []
    urls = []
    for hit in hits:
        post = filtered_posts[hit['corpus_id']]
        hits_titles.append(post['title'])
        hits_scores.append("{:.3f}".format(hit['score']))
        urls.append(f"https://stackoverflow.com/q/{post['id']}")

    return hits_titles, hits_scores, urls


def text_cluster(anchor: str, n_answers: int, model_name: str, model_dict: dict):
    # Proceeding with model
    print(model_name)
    assert model_name == "distilbert_qa"
    model = load_model(model_name, model_dict)

    # Creating embeddings
    query_emb = model.encode(anchor, convert_to_tensor=True)[None, :]

    print("loading embeddings")
    corpus_emb = load_embeddings()

    # Getting hits
    hits = util.semantic_search(query_emb, corpus_emb, score_function=util.dot_score, top_k=n_answers)[0]

    filtered_posts = filter_questions("python")

    hits_dict = [filtered_posts[hit['corpus_id']] for hit in hits]
    hits_dict.append(dict(id = '1', title = anchor, tags = ['']))

    hits_emb = torch.stack([corpus_emb[hit['corpus_id']] for hit in hits])
    hits_emb = torch.cat((hits_emb, query_emb))

    # Dimensionality reduction with t-SNE
    tsne = TSNE(n_components=3, verbose=1, perplexity=15, n_iter=1000)
    tsne_results = tsne.fit_transform(hits_emb.cpu())
    df = pd.DataFrame(hits_dict)
    tags = list(df['tags'])

    counter = Counter(tags[0])
    for i in tags[1:]:
        counter.update(i)

    df_tags = pd.DataFrame(counter.most_common(), columns=['Tag', 'Mentions'])
    most_common_tags = list(df_tags['Tag'])[1:5]

    labels = []

    for tags_list in list(df['tags']):
        for common_tag in most_common_tags:
            if common_tag in tags_list:
                labels.append(common_tag)
                break
            elif common_tag != most_common_tags[-1]:
                continue
            else:
                labels.append('others')

    df['title'] = [post['title'] for post in hits_dict]
    df['labels'] = labels
    df['tsne_x'] = tsne_results[:, 0]
    df['tsne_y'] = tsne_results[:, 1]
    df['tsne_z'] = tsne_results[:, 2]

    df['size'] = [2 for i in range(len(df))]

    # Making the query bigger than the rest of the observations
    df['size'][len(df) - 1] = 10
    df['labels'][len(df) - 1] = 'QUERY'
    import plotly.express as px

    fig = px.scatter_3d(df, x='tsne_x', y='tsne_y', z='tsne_z', color='labels', size='size',
                        color_discrete_sequence=px.colors.qualitative.D3, hover_data=[df.title])
    return fig