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A download function and examples app for Streamlit
import base64
import os
import json
import pickle
import uuid
import re
import streamlit as st
import pandas as pd
def download_button(object_to_download, download_filename, button_text, pickle_it=False):
"""
Generates a link to download the given object_to_download.
Params:
------
object_to_download: The object to be downloaded.
download_filename (str): filename and extension of file. e.g. mydata.csv,
some_txt_output.txt download_link_text (str): Text to display for download
link.
button_text (str): Text to display on download button (e.g. 'click here to download file')
pickle_it (bool): If True, pickle file.
Returns:
-------
(str): the anchor tag to download object_to_download
Examples:
--------
download_link(your_df, 'YOUR_DF.csv', 'Click to download data!')
download_link(your_str, 'YOUR_STRING.txt', 'Click to download text!')
"""
if pickle_it:
try:
object_to_download = pickle.dumps(object_to_download)
except pickle.PicklingError as e:
st.write(e)
return None
else:
if isinstance(object_to_download, bytes):
pass
elif isinstance(object_to_download, pd.DataFrame):
object_to_download = object_to_download.to_csv(index=False)
# Try JSON encode for everything else
else:
object_to_download = json.dumps(object_to_download)
try:
# some strings <-> bytes conversions necessary here
b64 = base64.b64encode(object_to_download.encode()).decode()
except AttributeError as e:
b64 = base64.b64encode(object_to_download).decode()
button_uuid = str(uuid.uuid4()).replace('-', '')
button_id = re.sub('\d+', '', button_uuid)
custom_css = f"""
<style>
#{button_id} {{
background-color: rgb(255, 255, 255);
color: rgb(38, 39, 48);
padding: 0.25em 0.38em;
position: relative;
text-decoration: none;
border-radius: 4px;
border-width: 1px;
border-style: solid;
border-color: rgb(230, 234, 241);
border-image: initial;
}}
#{button_id}:hover {{
border-color: rgb(246, 51, 102);
color: rgb(246, 51, 102);
}}
#{button_id}:active {{
box-shadow: none;
background-color: rgb(246, 51, 102);
color: white;
}}
</style> """
dl_link = custom_css + f'<a download="{download_filename}" id="{button_id}" href="data:file/txt;base64,{b64}">{button_text}</a><br></br>'
return dl_link
def file_selector(folder_path='.'):
filenames = os.listdir(folder_path)
selected_filename = st.selectbox('Select a file', filenames)
return os.path.join(folder_path, selected_filename)
if __name__ == '__main__':
st.markdown("""
## How to download files in Streamlit with download_button()
~> Below are use cases and code examples for the `download_button()`
function, which returns a clickable download link given your data
file as input.
See the `Show code example` at the bottom of each section for a
code snippet you can copy & paste.
[Recommend improvements here](https://discuss.streamlit.io/)
The download_button() function is an extension of a workaround based on
the discussions covered in more detail at [Awesome Streamlit](http://awesome-streamlit.org/).
Go to Gallery -> Select the App Dropdown -> Choose "File Download Workaround"
for more information.""")
st.markdown('-'*17)
# ---------------------
# Download from memory
# ---------------------
if st.checkbox('Download object from memory'):
st.write('~> Use if you want to save some data from memory (e.g. pd.DataFrame, dict, list, str, int)')
# Enter text for testing
s = st.selectbox('Select dtype', ['list', # TODO: Add more
'str',
'int',
'float',
'dict',
'bool',
'pd.DataFrame'])
filename = st.text_input('Enter output filename and ext (e.g. my-dataframe.csv, my-file.json, my-list.txt)', 'my-file.json')
# Pickle Rick
pickle_it = st.checkbox('Save as pickle file')
sample_df = pd.DataFrame({'x': list(range(10)), 'y': list(range(10))})
sample_dtypes = {'list': [1,'a', [2, 'c'], {'b': 2}],
'str': 'Hello Streamlit!',
'int': 17,
'float': 17.0,
'dict': {1: 'a', 'x': [2, 'c'], 2: {'b': 2}},
'bool': True,
'pd.DataFrame': sample_df}
# Display sample data
st.write(f'#### Sample `{s}` to be saved to `{filename}`')
st.code(sample_dtypes[s], language='python')
# Download sample
download_button_str = download_button(sample_dtypes[s], filename, f'Click here to download {filename}', pickle_it=pickle_it)
st.markdown(download_button_str, unsafe_allow_html=True)
if st.checkbox('Show code example '):
code_text = f"""
s = {sample_dtypes[s]}
download_button_str = download_button(s, '{filename}', 'Click here to download {filename}', pickle_it={pickle_it})
st.markdown(download_button_str, unsafe_allow_html=True)"""
st.code(code_text, language='python')
# --------------------------
# Select a file to download
# --------------------------
if st.checkbox('Select a file to download'):
st.write('~> Use if you want to test uploading / downloading a certain file.')
# Upload file for testing
folder_path = st.text_input('Enter directory: deafult .', '.')
filename = file_selector(folder_path=folder_path)
# Load selected file
with open(filename, 'rb') as f:
s = f.read()
download_button_str = download_button(s, filename, f'Click here to download {filename}')
st.markdown(download_button_str, unsafe_allow_html=True)
if st.checkbox('Show code example'):
code_text = f"""
with open('{filename}', 'rb') as f:
s = f.read()
download_button_str = download_button(s, '{filename}', 'Click here to download {filename}')
st.markdown(download_button_str, unsafe_allow_html=True)"""
st.code(code_text, language='python')
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