solution-chapter-4-v2.ipynb

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    "In this problem we need to find a way to transform the date from relative into absolute format. "
   ]
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   "cell_type": "markdown",
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   "source": [
    "We can use `re` library to parse the required information (number and units) and `datetime` library to convert date into datetime format. "
   ]
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    "from datetime import datetime, timedelta #datetime format and timedelta to calculate the distance to substract\n",
    "import re\n",
    "\n",
    "def autocorrect(x:str) -> str:\n",
    "    #dlt is a number with any number of digits, period is a text between number and 'ago'\n",
    "    dlt, period=re.findall(r'(\\d+) (.*?) ago',x)[0] \n",
    "    dlt=int(dlt)  #convert from str to int\n",
    "    period=period.rstrip('s')+'s' #according to documentation of timedelta, period is specified as argument in plural form.\n",
    "    \n",
    "    #from current datetime we substract the timedelta. In order to generalize the solution I decided to use eval function that \n",
    "    #evaluates the text as a python command. That allows us to use period as variable argument for timedelta function.\n",
    "    #Finally we convert the datetime output into string of specified format.\n",
    "    return (datetime.now()-eval('timedelta('+eval('period')+'=dlt)')).strftime('%d/%m/%Y') "
   ]
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   "cell_type": "code",
   "execution_count": 4,
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    {
     "data": {
      "text/plain": [
       "'18/03/2021'"
      ]
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     "execution_count": 4,
     "metadata": {},
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   "source": [
    "datetime.now().strftime('%d/%m/%Y') "
   ]
  },
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   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'14/03/2021'"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "autocorrect('4 days ago')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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