app.py

import time
import streamlit as st
import torch
import string



from transformers import BertTokenizer, BertForMaskedLM

st.set_page_config(page_title='Compare pretrained BERT models qualitatively', page_icon=None, layout='centered', initial_sidebar_state='auto')

@st.cache()
def load_bert_model(model_name):
  try:
    bert_tokenizer = BertTokenizer.from_pretrained(model_name,do_lower_case
    =False)
    bert_model = BertForMaskedLM.from_pretrained(model_name).eval()
    return bert_tokenizer,bert_model
  except Exception as e:
    pass



  
def decode(tokenizer, pred_idx, top_clean):
  ignore_tokens = string.punctuation
  tokens = []
  for w in pred_idx:
    token = ''.join(tokenizer.decode(w).split())
    if token not in ignore_tokens and len(token) > 1 and not token.startswith('.') and not token.startswith('['):
      #tokens.append(token.replace('##', ''))
      tokens.append(token)
  return '\n'.join(tokens[:top_clean])

def encode(tokenizer, text_sentence, add_special_tokens=True):
  
  text_sentence = text_sentence.replace('<mask>', tokenizer.mask_token)

  tokenized_text = tokenizer.tokenize(text_sentence) 
  input_ids = torch.tensor([tokenizer.encode(text_sentence, add_special_tokens=add_special_tokens)])
  if (tokenizer.mask_token in text_sentence.split()):
    mask_idx = torch.where(input_ids == tokenizer.mask_token_id)[1].tolist()[0]
  else:
    mask_idx = 0
  return input_ids, mask_idx,tokenized_text

def get_all_predictions(text_sentence, model_name,top_clean=5):
  bert_tokenizer = st.session_state['bert_tokenizer']
  bert_model = st.session_state['bert_model']
  top_k = st.session_state['top_k']
  
    # ========================= BERT =================================
  input_ids, mask_idx,tokenized_text = encode(bert_tokenizer, text_sentence)
   
  with torch.no_grad():
    predict = bert_model(input_ids)[0]
  bert = decode(bert_tokenizer, predict[0, mask_idx, :].topk(top_k*10).indices.tolist(), top_clean)
  cls = decode(bert_tokenizer, predict[0, 0, :].topk(top_k*10).indices.tolist(), top_clean)
  
  if ("[MASK]" in text_sentence or "<mask>" in text_sentence):
    return {'Input sentence':text_sentence,'Tokenized text': tokenized_text, 'results_count':top_k,'Model':model_name,'Masked position': bert,'[CLS]':cls}
  else:
    return {'Input sentence':text_sentence,'Tokenized text': tokenized_text,'results_count':top_k,'Model':model_name,'[CLS]':cls}

def get_bert_prediction(input_text,top_k,model_name):
  try:
    #input_text += ' <mask>'
    res = get_all_predictions(input_text,model_name, top_clean=int(top_k))
    return res
  except Exception as error:
    pass
    
 
def run_test(sent,top_k,model_name):
  start = None
  if (st.session_state['bert_tokenizer'] is None):
        st.info("Loading model:" + st.session_state['model_name'])
        st.session_state['bert_tokenizer'], st.session_state['bert_model']  = load_bert_model(st.session_state['model_name'])
  with st.spinner("Computing"):
          start = time.time()
          try:
            res = get_bert_prediction(sent,st.session_state['top_k'],st.session_state['model_name'])
            st.caption("Results in JSON")
            st.json(res)
            
          except Exception as e:
            st.error("Some error occurred during prediction" + str(e))
            st.stop()
  if start is not None:
    st.text(f"prediction took {time.time() - start:.2f}s")
    
def on_text_change():

  text = st.session_state.my_text
  run_test(text,st.session_state['top_k'],st.session_state['model_name'])

def on_option_change():

  text = st.session_state.my_choice
  #st.info("Preselected text chosen:" + text)
  run_test(text,st.session_state['top_k'],st.session_state['model_name'])
  
def on_results_count_change():

   st.session_state['top_k'] = int(st.session_state.my_slider)
   st.info("Results count changed " + str(st.session_state['top_k']))

def on_model_change1():
  st.session_state['model_name'] = st.session_state.my_model1
  st.info("Pre-selected model chosen: " + st.session_state['model_name'])
  st.session_state['bert_tokenizer'], st.session_state['bert_model']  = load_bert_model(st.session_state['model_name'])

def on_model_change2(): 
  st.session_state['model_name'] = st.session_state.my_model2
  st.info("Custom model chosen: " + st.session_state['model_name'])
  st.session_state['bert_tokenizer'], st.session_state['bert_model']  = load_bert_model(st.session_state['model_name'])
  
def init_selectbox():
  st.selectbox(
     'Choose any of these sentences or type any text below',
     ('', "[MASK] who lives in New York and works for XCorp suffers from Parkinson's", "Lou Gehrig who lives in [MASK] and works for XCorp suffers from Parkinson's","Lou Gehrig who lives in New York and works       for [MASK] suffers from Parkinson's","Lou Gehrig who lives in New York and works for XCorp suffers from [MASK]","[MASK] who lives in New York and works for XCorp suffers from Lou Gehrig's", "Parkinson who      lives in [MASK] and works for XCorp suffers from Lou Gehrig's","Parkinson who lives in New York and works for [MASK] suffers from Lou Gehrig's","Parkinson who lives in New York and works for XCorp suffers      from [MASK]","Lou Gehrig","Parkinson","Lou Gehrigh's is a [MASK]","Parkinson is a [MASK]","New York is a [MASK]","New York","XCorp","XCorp is a [MASK]","acute lymphoblastic leukemia","acute lymphoblastic       leukemia is a [MASK]"),on_change=on_option_change,key='my_choice') 
  
def init_session_states():
  if 'top_k' not in st.session_state:
    st.session_state['top_k'] = 20
  if 'bert_tokenizer' not in st.session_state:
    st.session_state['bert_tokenizer'] = None
  if 'bert_model' not in st.session_state:
    st.session_state['bert_model'] = None
  if 'model_name' not in st.session_state:
    st.session_state['model_name'] = "ajitrajasekharan/biomedical"

def main():
  init_session_states()
  

  
  st.markdown("<h3 style='text-align: center;'>Compare pretrained BERT models qualitatively</h3>", unsafe_allow_html=True)
  st.markdown("""
        <small style="font-size:20px; color: #2f2f2f"><br/>Why compare pretrained models <b>before fine-tuning</b>?</small><br/><small style="font-size:16px; color: #7f7f7f">Pretrained BERT models can be used as is, <a href="https://ajitrajasekharan.github.io/2021/01/02/my-first-post.html"><b>with no fine tuning to perform tasks like NER.</b><br/></a>This can be done ideally by using both fill-mask and CLS predictions, or minimally using fill-mask predictions alone if they are adequate</small>
        """, unsafe_allow_html=True)

  st.write("This app can be used to examine both fill-mask predictions as well as the neighborhood of CLS vector")
  st.write("   - To examine fill-mask predictions, enter the token [MASK] or <mask> in a sentence")
  st.write("   - To examine just the [CLS] vector, enter a word/phrase or sentence. Example: eGFR or EGFR or non small cell lung cancer")
  st.sidebar.slider("Select count of predictions to display", 1 , 50, 20,key='my_slider',on_change=on_results_count_change) #some times it is possible to have less words


  try:
      st.sidebar.selectbox(label='Select Model to Apply',  options=['ajitrajasekharan/biomedical', 'bert-base-cased','bert-large-cased','microsoft/BiomedNLP-PubMedBERT-base-uncased-abstract-fulltext','allenai/scibert_scivocab_cased','dmis-lab/biobert-v1.1'], index=0,  key = "my_model1",on_change=on_model_change1)
      init_selectbox()
      st.text_input("Enter text below", "",on_change=on_text_change,key='my_text')
      st.text_input("Model not listed on left? Type the model name (fill-mask BERT models only)", "",key="my_model2",on_change=on_model_change2)

      st.info("Current status:")
      st.info("Selected results count = " + str(st.session_state['top_k']))
      st.info("Selected Model name = " + st.session_state['model_name'])
      
      #if (st.session_state['bert_tokenizer'] is None):
      #  st.session_state['bert_tokenizer'], st.session_state['bert_model']  = load_bert_model(st.session_state['model_name'])
      
      

  except Exception as e:
    st.error("Some error occurred during loading" + str(e))
    st.stop()  
	
  st.write("---")
  
 

if __name__ == "__main__":
   main()