app.py

import torch
import tokenizers

import pandas as pd
import streamlit as st
import torch.nn as nn
from transformers import RobertaTokenizer, RobertaModel


@st.cache(suppress_st_warning=True)
def init_model():
    model = RobertaModel.from_pretrained("roberta-large-mnli")

    model.pooler = nn.Sequential(
        nn.Linear(1024, 256),
        nn.LayerNorm(256),
        nn.ReLU(),
        nn.Linear(256, 8),
        nn.Sigmoid()
    )
    
    model_path = 'model.pt'
    model.load_state_dict(torch.load(model_path, map_location=torch.device("cpu")))
    model.eval()
    return model

cats = ['Computer Science', 'Economics', 'Electrical Engineering', 
        'Mathematics', 'Physics', 'Biology', 'Finance', 'Statistics']

def predict(outputs):
    top = 0
    probs = nn.functional.softmax(outputs, dim=1).tolist()[0]
    
    top_cats = []
    top_probs = []

    for prob, cat in sorted(zip(probs, cats), reverse=True):
        if top < 95:
            percent = prob * 100
            top += percent
            top_cats.append(cat)
            top_probs.append(prob)
            
    chart_data = pd.DataFrame(top_probs, columns=top_cats)
    st.bar_chart(chart_data)

tokenizer = RobertaTokenizer.from_pretrained("roberta-large-mnli")
model = init_model()
        
st.markdown("### Title")

title = st.text_area("* Enter title (required)", height=20)

st.markdown("### Abstract")

abstract = st.text_area("Enter abstract", height=200)

if not title:
    st.warning("Please fill out so required fields")
else:    
    st.markdown("### Result")
    encoded_input = tokenizer(title + '. ' + abstract, return_tensors='pt', padding=True, 
                          max_length = 512, truncation=True)
    with torch.no_grad():
        outputs = model(**encoded_input).pooler_output[:, 0, :]
        predict(outputs)