data-science-ipython-notebooks/python-data/datetime.ipynb

{
 "metadata": {
  "name": "",
  "signature": "sha256:4dcac17430f8456d8b357f87e754eeda54837fbcd49ef8901953fec4b2dcab52"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Dates and Times"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "* Basics\n",
      "* strftime\n",
      "* strptime\n",
      "* timedelta"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Basics"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from datetime import datetime, date, time"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "year = 2015\n",
      "month = 1\n",
      "day = 20\n",
      "hour = 7\n",
      "minute = 28\n",
      "second = 15"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt = datetime(year, month, day, hour, minute, second)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt.hour, dt.minute, dt.second"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 4,
       "text": [
        "(7, 28, 15)"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Extract the equivalent date object:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt.date()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 5,
       "text": [
        "datetime.date(2015, 1, 20)"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Extract the equivalent time object:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt.time()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 6,
       "text": [
        "datetime.time(7, 28, 15)"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "When aggregating or grouping time series data, it is sometimes useful to replace fields of a series of datetimes such as zeroing out the minute and second fields:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt.replace(minute=0, second=0)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 7,
       "text": [
        "datetime.datetime(2015, 1, 20, 7, 0)"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## strftime"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Format a datetime string:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt.strftime('%m/%d/%Y %H:%M')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": [
        "'01/20/2015 07:28'"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## strptime"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Convert a string into a datetime object:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "datetime.strptime('20150120', '%Y%m%d')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 9,
       "text": [
        "datetime.datetime(2015, 1, 20, 0, 0)"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## timedelta"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Get the current datetime:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt_now = datetime.now()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 10
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Subtract two datetime fields to create a timedelta:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "delta = dt_now - dt\n",
      "delta"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 11,
       "text": [
        "datetime.timedelta(6, 40171, 885211)"
       ]
      }
     ],
     "prompt_number": 11
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Add a datetime and a timedelta to get a new datetime:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dt + delta"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 12,
       "text": [
        "datetime.datetime(2015, 1, 26, 18, 37, 46, 885211)"
       ]
      }
     ],
     "prompt_number": 12
    }
   ],
   "metadata": {}
  }
 ]
}