{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "view-in-github"
   },
   "source": [
    "<a href=\"https://colab.research.google.com/github/apache/beam/blob/master/examples/notebooks/documentation/transforms/python/elementwise/keys-py.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open in Colab\"/></a>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "view-the-docs-top"
   },
   "source": [
    "<table align=\"left\"><td><a target=\"_blank\" href=\"https://beam.apache.org/documentation/transforms/python/elementwise/keys\"><img src=\"https://beam.apache.org/images/logos/full-color/name-bottom/beam-logo-full-color-name-bottom-100.png\" width=\"32\" height=\"32\" />View the docs</a></td></table>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "cellView": "form",
    "id": "_-code"
   },
   "outputs": [],
   "source": [
    "#@title Licensed under the Apache License, Version 2.0 (the \"License\")\n",
    "# Licensed to the Apache Software Foundation (ASF) under one\n",
    "# or more contributor license agreements. See the NOTICE file\n",
    "# distributed with this work for additional information\n",
    "# regarding copyright ownership. The ASF licenses this file\n",
    "# to you under the Apache License, Version 2.0 (the\n",
    "# \"License\"); you may not use this file except in compliance\n",
    "# with the License. You may obtain a copy of the License at\n",
    "#\n",
    "#   http://www.apache.org/licenses/LICENSE-2.0\n",
    "#\n",
    "# Unless required by applicable law or agreed to in writing,\n",
    "# software distributed under the License is distributed on an\n",
    "# \"AS IS\" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY\n",
    "# KIND, either express or implied. See the License for the\n",
    "# specific language governing permissions and limitations\n",
    "# under the License."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "keys"
   },
   "source": [
    "# Keys\n",
    "\n",
    "<script type=\"text/javascript\">\n",
    "localStorage.setItem('language', 'language-py')\n",
    "</script>\n",
    "\n",
    "<table align=\"left\" style=\"margin-right:1em\">\n",
    "  <td>\n",
    "    <a class=\"button\" target=\"_blank\" href=\"https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.Keys\"><img src=\"https://beam.apache.org/images/logos/sdks/python.png\" width=\"32px\" height=\"32px\" alt=\"Pydoc\"/> Pydoc</a>\n",
    "  </td>\n",
    "</table>\n",
    "\n",
    "<br/><br/><br/>\n",
    "\n",
    "Takes a collection of key-value pairs and returns the key of each element."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "setup"
   },
   "source": [
    "## Setup\n",
    "\n",
    "To run a code cell, you can click the **Run cell** button at the top left of the cell,\n",
    "or select it and press **`Shift+Enter`**.\n",
    "Try modifying a code cell and re-running it to see what happens.\n",
    "\n",
    "> To learn more about Colab, see\n",
    "> [Welcome to Colaboratory!](https://colab.sandbox.google.com/notebooks/welcome.ipynb).\n",
    "\n",
    "First, let's install the `apache-beam` module."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "id": "setup-code"
   },
   "outputs": [],
   "source": [
    "!pip install --quiet -U apache-beam"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "example"
   },
   "source": [
    "## Example\n",
    "\n",
    "In the following example, we create a pipeline with a `PCollection` of key-value pairs.\n",
    "Then, we apply `Keys` to extract the keys and discard the values."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "id": "example-code"
   },
   "outputs": [],
   "source": [
    "import apache_beam as beam\n",
    "\n",
    "with beam.Pipeline() as pipeline:\n",
    "  icons = (\n",
    "      pipeline\n",
    "      | 'Garden plants' >> beam.Create([\n",
    "          ('🍓', 'Strawberry'),\n",
    "          ('🥕', 'Carrot'),\n",
    "          ('🍆', 'Eggplant'),\n",
    "          ('🍅', 'Tomato'),\n",
    "          ('🥔', 'Potato'),\n",
    "      ])\n",
    "      | 'Keys' >> beam.Keys()\n",
    "      | beam.Map(print))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "example-2"
   },
   "source": [
    "<table align=\"left\" style=\"margin-right:1em\">\n",
    "  <td>\n",
    "    <a class=\"button\" target=\"_blank\" href=\"https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/snippets/transforms/elementwise/keys.py\"><img src=\"https://www.tensorflow.org/images/GitHub-Mark-32px.png\" width=\"32px\" height=\"32px\" alt=\"View source code\"/> View source code</a>\n",
    "  </td>\n",
    "</table>\n",
    "\n",
    "<br/><br/><br/>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "related-transforms"
   },
   "source": [
    "## Related transforms\n",
    "\n",
    "* [KvSwap](https://beam.apache.org/documentation/transforms/python/elementwise/kvswap) swaps the key and value of each element.\n",
    "* [Values](https://beam.apache.org/documentation/transforms/python/elementwise/values) for extracting the value of each element.\n",
    "\n",
    "<table align=\"left\" style=\"margin-right:1em\">\n",
    "  <td>\n",
    "    <a class=\"button\" target=\"_blank\" href=\"https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.util.html#apache_beam.transforms.util.Keys\"><img src=\"https://beam.apache.org/images/logos/sdks/python.png\" width=\"32px\" height=\"32px\" alt=\"Pydoc\"/> Pydoc</a>\n",
    "  </td>\n",
    "</table>\n",
    "\n",
    "<br/><br/><br/>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "view-the-docs-bottom"
   },
   "source": [
    "<table align=\"left\"><td><a target=\"_blank\" href=\"https://beam.apache.org/documentation/transforms/python/elementwise/keys\"><img src=\"https://beam.apache.org/images/logos/full-color/name-bottom/beam-logo-full-color-name-bottom-100.png\" width=\"32\" height=\"32\" />View the docs</a></td></table>"
   ]
  }
 ],
 "metadata": {
  "colab": {
   "name": "Keys - element-wise transform",
   "toc_visible": true
  },
  "kernelspec": {
   "display_name": "python3",
   "name": "python3"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}