如何使用python通过浏览器下载数据框

Posted 2023-03-29

【中文标题】如何使用python通过浏览器下载数据框

【英文标题】：How to make a dataframe download through browser using python

【发布时间】：2021-09-02 06:12:14

【问题描述】：

我有一个函数，它在函数末尾生成一个数据框，我将其导出为 Excel 工作表。 df.to_excel('response.xlsx') 这个 excel 文件被保存在我的工作目录中。 现在我将它作为 web 应用程序托管在 heroku 上的 Streamlit 中，但是一旦调用此函数，我希望将这个 excel 文件下载到用户的本地磁盘（普通浏览器下载）中。有什么办法吗？

【问题讨论】：

截至今天，2021 年 6 月 17 日，还没有正式的下载实现。然而。有这个解决方法：github.com/MarcSkovMadsen/awesome-streamlit/blob/master/gallery/…

Streamlit 现在支持原生下载blog.streamlit.io/0-88-0-release-notes

【参考方案1】：

来自streamlit 的Snehan Kekre 在this thread 中编写了以下解决方案。

streamlit as st
import pandas as pd
import io

import base64
import os
import json
import pickle
import uuid
import re


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)
            towrite = io.BytesIO()
            object_to_download = object_to_download.to_excel(towrite, encoding='utf-8', index=False, header=True)
            towrite.seek(0)

        # 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(towrite.read()).decode()

    button_uuid = str(uuid.uuid4()).replace('-', '')
    button_id = re.sub('\d+', '', button_uuid)

    custom_css = f""" 
        <style>
            #button_id 
                display: inline-flex;
                align-items: center;
                justify-content: center;
                background-color: rgb(255, 255, 255);
                color: rgb(38, 39, 48);
                padding: .25rem .75rem;
                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:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;base64,b64">button_text</a><br></br>'

    return dl_link


vals= ['A','B','C']
df= pd.DataFrame(vals, columns=["Title"])  

filename = 'my-dataframe.xlsx'
download_button_str = download_button(df, filename, f'Click here to download filename', pickle_it=False)
st.markdown(download_button_str, unsafe_allow_html=True)

我建议在该论坛上搜索主题。这段代码似乎至少有 3-4 种替代方案。

【参考方案2】：

Mark Madson 在 github 上发布了 this workaround。我从 repo 中取出它并粘贴在这里作为答案。

import base64
import pandas as pd
import streamlit as st
  
def st_csv_download_button(df):
    csv = df.to_csv(index=False) #if no filename is given, a string is returned
    b64 = base64.b64encode(csv.encode()).decode()
    href = f'<a href="data:file/csv;base64,b64">Download CSV File</a>'
    st.markdown(href, unsafe_allow_html=True)  

用法：

st_csv_download_button(my_data_frame)

右击+另存为。

我认为你可以通过 to_excel 而不是 to_csv 来做到这一点。