04_Loops.ipynb

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   "source": [
    "# Loops in Python"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "*** There are two types of loops in Python***\n",
    "- for\n",
    "- while."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## For loop"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For Loop\n",
    "Python's for takes an iterable (such as a  sequence or iterator) and traverses each element once.\n",
    "\n",
    "Example 1 :-\n",
    "```python\n",
    "for i in range(0,4):\n",
    "       print(i)\n",
    "```\n",
    "\n",
    "Example 2 :-\n",
    "```python\n",
    "for i in [1,2,3,4]:\n",
    "       print(i)\n",
    "```\n",
    "Example 3:-\n",
    "```python\n",
    "for i in (1,2,3,4):\n",
    "       print(i)\n",
    "```\n",
    "** Try for dictionary**"
   ]
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   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 : 11\n",
      "1 : 12\n",
      "2 : 13\n",
      "3 : 14\n"
     ]
    }
   ],
   "source": [
    "l = [11,12,13,14]\n",
    "for i in range(0, len(l)):\n",
    "    print(i, \":\", l[i])"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## \"while\" loops"
   ]
  },
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   "metadata": {},
   "source": [
    "Syntax: \n",
    "```python\n",
    "while expression:\n",
    "      while_suite\n",
    "```\n",
    "\n",
    "- The statement `while_suite` is executed continuously in a loop until the expression becomes zero or false"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "counter = 0\n",
    "while counter < 3:\n",
    "    print(counter)\n",
    "    counter += 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Nested Loops\n",
    "Example:-\n",
    "```python\n",
    "for i in range(0,9):\n",
    "    for j in range (1,5):\n",
    "        for k in range (1,3)\n",
    "            pass\n",
    "```\n",
    "- You can put any type of `loop` inside of any other type of loop. \n",
    "- For example a for loop can be inside a while loop or vice versa."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
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     "text": [
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n"
     ]
    }
   ],
   "source": [
    "my_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n",
    "for inner_list in my_list:\n",
    "    for val in inner_list:\n",
    "        print(val)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Loops control statements"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- Loop control statements change execution from its normal sequence\n",
    "- Python supports the following control statements\n",
    "    - break statement\n",
    "    - continue statement\n",
    "    - pass statement"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### break\n",
    "- It terminates the current loop and resumes execution at the next statement immediately after the loop\n",
    "- Can be used in  both for and while loop\n",
    "- break statement stops the execution of the innermost loop if we are using nested loop"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "l = [1, 2, 3]\n",
    "for each in l:\n",
    "    if each == 3:\n",
    "        break\n",
    "    print(each)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "3\n",
      "5\n",
      "6\n",
      "8\n",
      "7\n",
      "2\n",
      "4\n",
      "5\n",
      "0\n"
     ]
    }
   ],
   "source": [
    "t = (1, 2, 3, 5, 6, \"8\", 7, 2, 4,5,0)\n",
    "\n",
    "for each in t:\n",
    "    if isinstance(each, str):\n",
    "        pass\n",
    "    print(each)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Continue statement\n",
    "- Skips the remainder of the loop and immediately retest its condition prior to reiterating."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "4\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "for item in [1,2,3,4,5]:\n",
    "    if item == 3:\n",
    "        continue\n",
    "    print(item)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### pass statement\n",
    "- The pass statement in Python is used when a statement is required syntactically but you do not want any command or code to execute."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "dsdsd\n",
      "3\n",
      "4\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "for item in [1,2,3,4,5]:\n",
    "    if item == 3:\n",
    "        pass   # does nothing\n",
    "        print(\"dsdsd\")\n",
    "    print(item)"
   ]
  }
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