Add tutorial on structured data conversion.

This changes types.FloatInput to use tf.float32 for its feature_spec
attribute to address potential incompatibility with using tf.float64
type in TensorFlow Transform.

Makefile

@@ -7,6 +7,6 @@ test:
 	nosetests --with-coverage -v --cover-package=tfrecorder
 
 pylint:
-	pylint tfrecorder
+	pylint -j 0 tfrecorder
 
 .PHONY: all init test pylint 

samples/Convert-structured-data.ipynb

@@ -0,0 +1,383 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Convert structured data to TFRecords "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The autoreload extension is already loaded. To reload it, use:\n",
+      "  %reload_ext autoreload\n"
+     ]
+    }
+   ],
+   "source": [
+    "%load_ext autoreload\n",
+    "%autoreload 2"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "Error importing tfx_bsl_extension.arrow.array_util. Some tfx_bsl functionalities are not available"
+     ]
+    }
+   ],
+   "source": [
+    "import pandas as pd\n",
+    "import pathlib\n",
+    "\n",
+    "import tensorflow as tf\n",
+    "\n",
+    "import tfrecorder\n",
+    "from tfrecorder import input_schema\n",
+    "from tfrecorder import types"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Load [Titanic](https://www.openml.org/d/40945) dataset "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "data_path = pathlib.Path('/tmp/datasets/titanic.csv')\n",
+    "if not data_path.exists():\n",
+    "  tf.keras.utils.get_file(\n",
+    "      'titanic.csv',\n",
+    "      origin='https://web.stanford.edu/class/archive/cs/cs109/cs109.1166/stuff/titanic.csv',\n",
+    "      extract=False,\n",
+    "      cache_dir='/tmp', cache_subdir='datasets')\n",
+    "  \n",
+    "assert data_path.exists()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "df = pd.read_csv(str(data_path))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Add `split` column "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>Survived</th>\n",
+       "      <th>Pclass</th>\n",
+       "      <th>Name</th>\n",
+       "      <th>Sex</th>\n",
+       "      <th>Age</th>\n",
+       "      <th>Siblings/Spouses Aboard</th>\n",
+       "      <th>Parents/Children Aboard</th>\n",
+       "      <th>Fare</th>\n",
+       "      <th>split</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>0</td>\n",
+       "      <td>3</td>\n",
+       "      <td>Mr. Owen Harris Braund</td>\n",
+       "      <td>male</td>\n",
+       "      <td>22.0</td>\n",
+       "      <td>1</td>\n",
+       "      <td>0</td>\n",
+       "      <td>7.2500</td>\n",
+       "      <td>TRAIN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>1</td>\n",
+       "      <td>1</td>\n",
+       "      <td>Mrs. John Bradley (Florence Briggs Thayer) Cum...</td>\n",
+       "      <td>female</td>\n",
+       "      <td>38.0</td>\n",
+       "      <td>1</td>\n",
+       "      <td>0</td>\n",
+       "      <td>71.2833</td>\n",
+       "      <td>TRAIN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>1</td>\n",
+       "      <td>3</td>\n",
+       "      <td>Miss. Laina Heikkinen</td>\n",
+       "      <td>female</td>\n",
+       "      <td>26.0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>7.9250</td>\n",
+       "      <td>TRAIN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>1</td>\n",
+       "      <td>1</td>\n",
+       "      <td>Mrs. Jacques Heath (Lily May Peel) Futrelle</td>\n",
+       "      <td>female</td>\n",
+       "      <td>35.0</td>\n",
+       "      <td>1</td>\n",
+       "      <td>0</td>\n",
+       "      <td>53.1000</td>\n",
+       "      <td>TRAIN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>4</th>\n",
+       "      <td>0</td>\n",
+       "      <td>3</td>\n",
+       "      <td>Mr. William Henry Allen</td>\n",
+       "      <td>male</td>\n",
+       "      <td>35.0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>8.0500</td>\n",
+       "      <td>TRAIN</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   Survived  Pclass                                               Name  \\\n",
+       "0         0       3                             Mr. Owen Harris Braund   \n",
+       "1         1       1  Mrs. John Bradley (Florence Briggs Thayer) Cum...   \n",
+       "2         1       3                              Miss. Laina Heikkinen   \n",
+       "3         1       1        Mrs. Jacques Heath (Lily May Peel) Futrelle   \n",
+       "4         0       3                            Mr. William Henry Allen   \n",
+       "\n",
+       "      Sex   Age  Siblings/Spouses Aboard  Parents/Children Aboard     Fare  \\\n",
+       "0    male  22.0                        1                        0   7.2500   \n",
+       "1  female  38.0                        1                        0  71.2833   \n",
+       "2  female  26.0                        0                        0   7.9250   \n",
+       "3  female  35.0                        1                        0  53.1000   \n",
+       "4    male  35.0                        0                        0   8.0500   \n",
+       "\n",
+       "   split  \n",
+       "0  TRAIN  \n",
+       "1  TRAIN  \n",
+       "2  TRAIN  \n",
+       "3  TRAIN  \n",
+       "4  TRAIN  "
+      ]
+     },
+     "execution_count": 5,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "df['split'] = 'TRAIN'\n",
+    "df.head()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Convert to TFRecords "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "application/javascript": [
+       "\n",
+       "        if (typeof window.interactive_beam_jquery == 'undefined') {\n",
+       "          var jqueryScript = document.createElement('script');\n",
+       "          jqueryScript.src = 'https://code.jquery.com/jquery-3.4.1.slim.min.js';\n",
+       "          jqueryScript.type = 'text/javascript';\n",
+       "          jqueryScript.onload = function() {\n",
+       "            var datatableScript = document.createElement('script');\n",
+       "            datatableScript.src = 'https://cdn.datatables.net/1.10.20/js/jquery.dataTables.min.js';\n",
+       "            datatableScript.type = 'text/javascript';\n",
+       "            datatableScript.onload = function() {\n",
+       "              window.interactive_beam_jquery = jQuery.noConflict(true);\n",
+       "              window.interactive_beam_jquery(document).ready(function($){\n",
+       "                \n",
+       "              });\n",
+       "            }\n",
+       "            document.head.appendChild(datatableScript);\n",
+       "          };\n",
+       "          document.head.appendChild(jqueryScript);\n",
+       "        } else {\n",
+       "          window.interactive_beam_jquery(document).ready(function($){\n",
+       "            \n",
+       "          });\n",
+       "        }"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    },
+    {
+     "data": {
+      "application/javascript": [
+       "\n",
+       "        var import_html = () => {\n",
+       "          ['https://raw.githubusercontent.com/PAIR-code/facets/1.0.0/facets-dist/facets-jupyter.html'].forEach(href => {\n",
+       "            var link = document.createElement('link');\n",
+       "            link.rel = 'import'\n",
+       "            link.href = href;\n",
+       "            document.head.appendChild(link);\n",
+       "          });\n",
+       "        }\n",
+       "        if ('import' in document.createElement('link')) {\n",
+       "          import_html();\n",
+       "        } else {\n",
+       "          var webcomponentScript = document.createElement('script');\n",
+       "          webcomponentScript.src = 'https://cdnjs.cloudflare.com/ajax/libs/webcomponentsjs/1.3.3/webcomponents-lite.js';\n",
+       "          webcomponentScript.type = 'text/javascript';\n",
+       "          webcomponentScript.onload = function(){\n",
+       "            import_html();\n",
+       "          };\n",
+       "          document.head.appendChild(webcomponentScript);\n",
+       "        }"
+      ]
+     },
+     "metadata": {},
+     "output_type": "display_data"
+    }
+   ],
+   "source": [
+    "results = tfrecorder.create_tfrecords(\n",
+    "    df, \n",
+    "    './tfrecords', \n",
+    "    schema=input_schema.Schema({\n",
+    "        'Survived': types.IntegerInput,\n",
+    "        'Pclass': types.IntegerInput,\n",
+    "        'Name': types.StringInput,\n",
+    "        'Sex': types.StringInput,\n",
+    "        'Age': types.FloatInput,\n",
+    "        'Siblings/Spuses Aboard': types.IntegerInput,\n",
+    "        'Parents/Children Aboard': types.IntegerInput,\n",
+    "        'Fare': types.FloatInput,\n",
+    "        'split': types.SplitKey,\n",
+    "    })\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Load a dataset from the generated TFRecord files "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "datasets = tfrecorder.load('tfrecords/tfrecorder-20201014-115328-create-tfrecords')"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Age: <dtype: 'float32'>\n",
+      "Fare: <dtype: 'float32'>\n",
+      "Name: <dtype: 'string'>\n",
+      "Parents/Children Aboard: <dtype: 'int64'>\n",
+      "Pclass: <dtype: 'int64'>\n",
+      "Sex: <dtype: 'string'>\n",
+      "Siblings/Spuses Aboard: <dtype: 'int64'>\n",
+      "Survived: <dtype: 'int64'>\n",
+      "split: <dtype: 'string'>\n"
+     ]
+    }
+   ],
+   "source": [
+    "for x in datasets['TRAIN'].take(1):\n",
+    "  for k, v in x.items():\n",
+    "    print(f'{k}: {v.dtype}')"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.8"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}