examples/gallery/simple/file_download_examples.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# File Download Example\n",
    "\n",
    "The **purpose** of this notebook is to provide code examples and **code snippets** that enable you to quickly add FileDownload to your Panel dashboard or application."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import pandas as pd\n",
    "import panel as pn\n",
    "from io import BytesIO\n",
    "\n",
    "pn.extension(sizing_mode=\"stretch_width\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Source: Pandas DataFrame"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "data=pd.DataFrame(np.random.randn(100, 4), columns=list('ABCD'))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Target: `.csv`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def get_csv():\n",
    "    return BytesIO(data.to_csv().encode())\n",
    "\n",
    "file_download_csv = pn.widgets.FileDownload(filename=\"data.csv\", callback=get_csv, button_type=\"primary\")\n",
    "file_download_csv"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Target: `.csv.zip`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def get_csv_zip():\n",
    "    output = BytesIO()\n",
    "    output.name = \"data.csv\"\n",
    "    data.to_csv(output, compression=\"zip\")\n",
    "    output.seek(0)\n",
    "    return output\n",
    "\n",
    "file_download_csv_zip = pn.widgets.FileDownload(filename=\"data.csv.zip\", callback=get_csv_zip, button_type=\"primary\")\n",
    "file_download_csv_zip"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Target: `.xlsx`\n",
    "\n",
    "Please note you need to install one of the packages\n",
    "\n",
    "- [XlsxWriter](https://xlsxwriter.readthedocs.io/index.html) or\n",
    "- [OpenPyXL](https://openpyxl.readthedocs.io/en/stable/)\n",
    "\n",
    "to be able to use the `.to_excel` method of a DataFrame."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def get_xlsx():\n",
    "    output = BytesIO()\n",
    "    writer = pd.ExcelWriter(output, engine='xlsxwriter')\n",
    "    data.to_excel(writer, sheet_name=\"Data\")\n",
    "    writer.save() # Important!\n",
    "    output.seek(0) # Important!\n",
    "    return output\n",
    "\n",
    "file_download_xlsx = pn.widgets.FileDownload(filename=\"data.xlsx\", callback=get_xlsx, button_type=\"primary\")\n",
    "file_download_xlsx"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Target: `.json`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def get_json():\n",
    "    return BytesIO(data.to_json(orient=\"records\").encode())\n",
    "\n",
    "file_download_json = pn.widgets.FileDownload(filename=\"data.json\", callback=get_json, button_type=\"primary\")\n",
    "file_download_json"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Target: `.parquet`\n",
    "\n",
    "Please note you need to have the `pyarrow` package installed for this to work."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def get_parquet():\n",
    "    output = BytesIO()\n",
    "    output.name = \"data.parquet\"\n",
    "    data.to_parquet(output)\n",
    "    output.seek(0)\n",
    "    return output\n",
    "\n",
    "file_download_parquet = pn.widgets.FileDownload(filename=\"data.parquet\", callback=get_parquet, button_type=\"primary\")\n",
    "file_download_parquet"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Contributions\n",
    "\n",
    "Example Contributions are very welcome. For example for `DataFrame` to `html` or `pdf`."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## App\n",
    "\n",
    "Lets wrap it into nice template that can be served via `panel serve file_download_examples.ipynb`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "pn.template.FastListTemplate(\n",
    "    site=\"Panel\", \n",
    "    title=\"File Download\", \n",
    "    main=[\n",
    "        \"This app demonstrates how to **download a Pandas DataFrame** using different formats.\",\n",
    "        pn.Column(\n",
    "            pn.pane.HTML(\"<div style='font-size: 100px;text-align: center'>🐼</div>\", height=75, margin=(50,5,10,5)),\n",
    "            file_download_csv, file_download_csv_zip, file_download_xlsx, file_download_json, file_download_parquet),\n",
    "    ], main_max_width=\"768px\",\n",
    ").servable();"
   ]
  }
 ],
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