Datetime library added

python_tips_2.ipynb

@@ -585,6 +585,157 @@
     "for i in generator([1,2,3,4]):\n",
     "    print(i)"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Datetime\n",
+    "\n",
+    "The datetime module helps programmers manage and manipulate dates and times in Python with ease. This module is builtin, and further explanation and examples are to be found in the [documentation](https://docs.python.org/3/library/datetime.html)."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "datetime.datetime(2018, 9, 27, 11, 2, 34, 623437)"
+      ]
+     },
+     "execution_count": 6,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "from datetime import datetime\n",
+    "\n",
+    "# Display the (llocal!) current time and date\n",
+    "datetime.now()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "As you can see, we now have a datetime object, which has the following attributes: year, month, day, hour, minute, seconds, micro-seconds.\n",
+    "We can also extract just the data we need from the datetime object, as follows."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Today is the 27 day of month 9, and the year is 2018!\n"
+     ]
+    }
+   ],
+   "source": [
+    "now_datetime_object = datetime.now()\n",
+    "\n",
+    "# Extract only certain data\n",
+    "\n",
+    "now_year = now_datetime_object.year\n",
+    "now_month = now_datetime_object.month\n",
+    "now_day = now_datetime_object.day\n",
+    "\n",
+    "print('Today is the {} day of month {}, and the year is {}!'.format(now_day, now_month, now_year))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    ".. of month 9 looks quite bad.\n",
+    "That's where the method strftime() comes into play."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The current month is September.\n"
+     ]
+    }
+   ],
+   "source": [
+    "# strftime() formats datetime objects into readable strings\n",
+    "\n",
+    "print('The current month is {}.'.format(now_datetime_object.strftime(\"%B\")))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "strftime() can generally be used to format datetime objects."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Today's date is 27-09-2018, and be careful; now it is not a datetimeobject!\n",
+      "        it is actually <class 'str'>!\n"
+     ]
+    }
+   ],
+   "source": [
+    "pretty_format = now_datetime_object.strftime('%d-%m-%Y')\n",
+    "print(\"Today's date is {}, and be careful; now it is not a datetimeobject!\\n \\\n",
+    "       it is actually {}!\".format(pretty_format, type(pretty_format)))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "To get a date X days\\months\\etc from now, we use timedelta()."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "I started studying in university back in 21-10-2015, and I'll finish in 17-10-2018\n"
+     ]
+    }
+   ],
+   "source": [
+    "from datetime import timedelta\n",
+    "\n",
+    "# School lasts about three years, so we calculate the time difference between starting university time and three years \n",
+    "# (or 3 * 52 weeks) from this time\n",
+    "\n",
+    "start_uni_time = datetime(2015, 10, 21)\n",
+    "end_uni_time = start_uni_time + timedelta(weeks=52 * 3)\n",
+    "print(\"I started studying in university back in {}, and I'll finish in {}\".format(\n",
+    "       start_uni_time.strftime('%d-%m-%Y'), end_uni_time.strftime('%d-%m-%Y')))"
+   ]
   }
  ],
  "metadata": {