inplace_transform-column.ipynb

{
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   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "  first_name _last_name  _year_of_birth  _year_of_death\n",
      "0      Isaac     Newton            1642            1726\n",
      "1     Albert   Einstein            1879            1955\n",
      "2      James    Maxwell            1831            1879\n",
      "3      Henri   Poincaré            1854            1912\n"
     ]
    }
   ],
   "source": [
    "from io import StringIO\n",
    "import pandas as pd\n",
    "import janitor\n",
    "\n",
    "donnees = \"\"\"First name, Last name, Year of birth, Year of death\n",
    "Isaac, Newton, 1642, 1726\n",
    "Albert, Einstein, 1879, 1955\n",
    "James, Maxwell, 1831, 1879\n",
    "Henri, Poincaré, 1854, 1912\"\"\"\n",
    "\n",
    "df = pd.read_csv(StringIO(donnees)).clean_names()\n",
    "\n",
    "column_name = \"_year_of_birth\"\n",
    "function = lambda x: x - 18\n",
    "\n",
    "print(df)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "  first_name _last_name  _year_of_birth  _year_of_death\n",
      "0      Isaac     Newton            1642            1726\n",
      "1     Albert   Einstein            1879            1955\n",
      "2      James    Maxwell            1831            1879\n",
      "3      Henri   Poincaré            1854            1912\n"
     ]
    }
   ],
   "source": [
    "df.transform_column(\"_year_of_birth\", lambda x: x - 18)\n",
    "print(df)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "  first_name _last_name  _year_of_birth  _year_of_death\n",
      "0      Isaac     Newton            1642            1726\n",
      "1     Albert   Einstein            1879            1955\n",
      "2      James    Maxwell            1831            1879\n",
      "3      Henri   Poincaré            1854            1912\n"
     ]
    }
   ],
   "source": [
    "janitor.functions.transform_column(df, \"_year_of_birth\", lambda x: x + 18)\n",
    "print(df)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "  first_name _last_name  _year_of_birth  _year_of_death\n",
      "0      Isaac     Newton            1642            1726\n",
      "1     Albert   Einstein            1879            1955\n",
      "2      James    Maxwell            1831            1879\n",
      "3      Henri   Poincaré            1854            1912\n"
     ]
    }
   ],
   "source": [
    "dest_column_name = None\n",
    "elementwise = True\n",
    "if dest_column_name is None:\n",
    "    dest_column_name = column_name\n",
    "\n",
    "if elementwise:\n",
    "    result = df[column_name].apply(function)\n",
    "else:\n",
    "    result = function(df[column_name])\n",
    "\n",
    "df.assign(**{dest_column_name: result})\n",
    "print(df)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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