app.py

import streamlit as st
from transformers import AutoTokenizer, T5ForConditionalGeneration
import post_ocr

# Sidebar information
info = '''Welcome to the demo of the [swedish-ocr-correction](https://huggingface.co/viklofg/swedish-ocr-correction) model.

Enter or upload OCR output and the model will attempt to correct it.

:clock2:  Slow generation? Try a shorter input.
'''

# Example inputs
examples = {
    'Examples': None,
    'Example 1': 'En Gosse fur plats nu genast ! inetallyrkc, JU 83 Drottninggatan.',
    'Example 2': '— Storartad gåfva till Göteborgs Museum. Den i HandelstidniDgens g&rdagsnnmmer omtalade hvalfisken, sorn fångats i Frölnndaviken, har i dag af hr brukspatronen James Dickson blifvit inköpt för 1,500 rdr och skänkt till härvarande Museum.',
    'Example 3': 'Sn underlig race att ſtudera, desfa uppſinnare! utropar en Londontidnings fronifôr. Wet ni hur ſtort antalet är af patenter, ſom ſiſtlidet är utfärdades i British Patent Office? Jo, 14,000 ſty>en !! Det kan man ju fkalla en rif rd! Fjorton tuſen uppfinninnar! Herre Gud, hwilfet märkrwoärdigt tidehrvarf wi lefroa i!'
}


# Load model
@st.cache_resource
def load_model():
    return T5ForConditionalGeneration.from_pretrained('KBLab/swedish-ocr-correction')
model = load_model()


# Load tokenizer
@st.cache_resource
def load_tokenizer():
    return AutoTokenizer.from_pretrained('google/byt5-small')
tokenizer = load_tokenizer()


# Set model and tokenizer
post_ocr.set_model(model, tokenizer)


# Title
st.title(':memo: Swedish OCR correction')


# Input and output areas
tab1, tab2 = st.tabs(["Text input", "From file"])


# Initialize session states
if 'inputs' not in st.session_state:
    st.session_state.inputs = {'tab1': None, 'tab2': None}


if 'outputs' not in st.session_state:
    st.session_state.outputs = {'tab1': None, 'tab2': None}


# Sidebar (info)
with st.sidebar:
    st.header('About')
    st.markdown(info)


def handle_input(input_, id_):
    """Generate and display output"""

    # Put everything output-related in a bordered container
    with st.container(border=True):
        st.caption('Output')

        # Only update the output if the input has been updated
        if input_ and st.session_state.inputs[id_] != input_:
            st.session_state.inputs[id_] = input_
            with st.spinner('Generating...'):
                output = post_ocr.process(input_)
            st.session_state.outputs[id_] = output

        # This container is needed to display the `show changes` toggle
        # after the output text
        container = st.container()
        st.divider()
        show_changes = st.toggle('Show changes', key=f'show_changes_{id_}')

        with container:
            # Display output
            output = st.session_state.outputs[id_]
            if output is not None:
                st.write(post_ocr.diff(input_, output) if show_changes else output)


# Manual entry tab
with tab1:
    col1, col2 = st.columns([4, 1])

    with col2:
        example_title = st.selectbox('Examples', options=examples,
                               label_visibility='collapsed')

    with col1:
        text = st.text_area(
            label='Input text',
            value=examples[example_title],
            height=200,
            label_visibility='collapsed',
            placeholder='Enter OCR generated text or choose an example')

        if text is not None:
            handle_input(text, 'tab1')


# File upload tab
with tab2:
    uploaded_file = st.file_uploader('Choose a file', type='.txt')

    # Display file content
    if uploaded_file is not None:
        file_content = uploaded_file.getvalue().decode('utf-8')
        text = st.text_area('File content', value=file_content, height=300)
        handle_input(text, 'tab2')