app.py

import panel as pn
import pandas as pd
import os

pn.extension()

# Global variable to store the input value and the dataframe
stored_value = ""
df = None

# Define a callback to store the input value when the button is clicked
def store_value(event):
    global stored_value, df
    stored_value = text_input.value
    
    # Path to the dataset
    dataset_path = os.path.join("test_metadata/images", "Slide_B_DD1s1.one_1.tif.csv")
    
    # Load the dataset
    if os.path.exists(dataset_path):
        df = pd.read_csv(dataset_path)
        output_pane.object = f"Stored Value: {stored_value}\n\nDataFrame Head:\n{df.head().to_markdown(index=False)}"
    else:
        output_pane.object = f"Stored Value: {stored_value}\n\nError: File not found at {dataset_path}"

# Define the text input widget
text_input = pn.widgets.TextInput(
    name="Input Text",
    placeholder="Enter some text"
)

# Define the button widget
store_button = pn.widgets.Button(name='Store Value')
store_button.on_click(store_value)

# Define the output pane
output_pane = pn.pane.Markdown("Stored Value: ")

# Create a simple layout
layout = pn.Column(
    pn.pane.Markdown("### Simple Panel App"),
    text_input,
    store_button,
    output_pane,
    sizing_mode="stretch_width"
)

# Serve the app
layout.servable()