05.ipynb

{
	"cells": [

		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"#Control Flow Statements"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##If"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"if some_condition:\n",
				"    \n",
				"    algorithm"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 1,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"Hello\n"
				]
			}],
			"source": [
				"x = 12\n",
				"if x >10:\n",
				"    print \"Hello\""
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##If-else"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"if some_condition:\n",
				"    \n",
				"    algorithm\n",
				"    \n",
				"else:\n",
				"    \n",
				"    algorithm"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 2,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"hello\n"
				]
			}],
			"source": [
				"x = 12\n",
				"if x > 10:\n",
				"    print \"hello\"\n",
				"else:\n",
				"    print \"world\""
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##if-elif"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {
				"collapsed": false
			},
			"source": [
				"if some_condition:\n",
				"    \n",
				"    algorithm\n",
				"\n",
				"elif some_condition:\n",
				"    \n",
				"    algorithm\n",
				"\n",
				"else:\n",
				"    \n",
				"    algorithm"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 3,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"x<y\n"
				]
			}],
			"source": [
				"x = 10\n",
				"y = 12\n",
				"if x > y:\n",
				"    print \"x>y\"\n",
				"elif x < y:\n",
				"    print \"x<y\"\n",
				"else:\n",
				"    print \"x=y\""
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"if statement inside a if statement or if-elif or if-else are called as nested if statements."
			]
		},
		{
			"cell_type": "code",
			"execution_count": 4,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"x<y\n",
					"x=10\n"
				]
			}],
			"source": [
				"x = 10\n",
				"y = 12\n",
				"if x > y:\n",
				"    print \"x>y\"\n",
				"elif x < y:\n",
				"    print \"x<y\"\n",
				"    if x==10:\n",
				"        print \"x=10\"\n",
				"    else:\n",
				"        print \"invalid\"\n",
				"else:\n",
				"    print \"x=y\""
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##Loops"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"###For"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {
				"collapsed": false
			},
			"source": [
				"for variable in something:\n",
				"    \n",
				"    algorithm"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 5,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"0\n",
					"1\n",
					"2\n",
					"3\n",
					"4\n"
				]
			}],
			"source": [
				"for i in range(5):\n",
				"    print i"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"In the above example, i iterates over the 0,1,2,3,4. Every time it takes each value and executes the algorithm inside the loop. It is also possible to iterate over a nested list illustrated below."
			]
		},
		{
			"cell_type": "code",
			"execution_count": 6,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"[1, 2, 3]\n",
					"[4, 5, 6]\n",
					"[7, 8, 9]\n"
				]
			}],
			"source": [
				"list_of_lists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n",
				"for list1 in list_of_lists:\n",
				"        print list1"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"A use case of a nested for loop in this case would be,"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 7,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"1\n",
					"2\n",
					"3\n",
					"4\n",
					"5\n",
					"6\n",
					"7\n",
					"8\n",
					"9\n"
				]
			}],
			"source": [
				"list_of_lists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n",
				"for list1 in list_of_lists:\n",
				"    for x in list1:\n",
				"        print x"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"###While"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {
				"collapsed": false
			},
			"source": [
				"while some_condition:\n",
				"    \n",
				"    algorithm"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 8,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"1\n",
					"4\n",
					"Bye\n"
				]
			}],
			"source": [
				"i = 1\n",
				"while i < 3:\n",
				"    print(i ** 2)\n",
				"    i = i+1\n",
				"print('Bye')"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##Break"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"As the name says. It is used to break out of a loop when a condition becomes true when executing the loop."
			]
		},
		{
			"cell_type": "code",
			"execution_count": 9,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"0\n",
					"1\n",
					"2\n",
					"3\n",
					"4\n",
					"5\n",
					"6\n",
					"7\n"
				]
			}],
			"source": [
				"for i in range(100):\n",
				"    print i\n",
				"    if i>=7:\n",
				"        break"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##Continue"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"This continues the rest of the loop. Sometimes when a condition is satisfied there are chances of the loop getting terminated. This can be avoided using continue statement. "
			]
		},
		{
			"cell_type": "code",
			"execution_count": 10,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"0\n",
					"1\n",
					"2\n",
					"3\n",
					"4\n",
					"The end.\n",
					"The end.\n",
					"The end.\n",
					"The end.\n",
					"The end.\n"
				]
			}],
			"source": [
				"for i in range(10):\n",
				"    if i>4:\n",
				"        print \"The end.\"\n",
				"        continue\n",
				"    elif i<7:\n",
				"        print i"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"##List Comprehensions"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"Python makes it simple to generate a required list with a single line of code using list comprehensions. For example If i need to generate multiples of say 27 I write the code using for loop as,"
			]
		},
		{
			"cell_type": "code",
			"execution_count": 11,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"name": "stdout",
				"output_type": "stream",
				"text": [
					"[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]\n"
				]
			}],
			"source": [
				"res = []\n",
				"for i in range(1,11):\n",
				"    x = 27*i\n",
				"    res.append(x)\n",
				"print res"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"Since you are generating another list altogether and that is what is required, List comprehensions is a more efficient way to solve this problem."
			]
		},
		{
			"cell_type": "code",
			"execution_count": 12,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"data": {
					"text/plain": [
						"[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]"
					]
				},
				"execution_count": 12,
				"metadata": {},
				"output_type": "execute_result"
			}],
			"source": [
				"[27*x for x in range(1,11)]"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"That's it!. Only remember to enclose it in square brackets"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"Understanding the code, The first bit of the code is always the algorithm and then leave a space and then write the necessary loop. But you might be wondering can nested loops be extended to list comprehensions? Yes you can."
			]
		},
		{
			"cell_type": "code",
			"execution_count": 13,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"data": {
					"text/plain": [
						"[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]"
					]
				},
				"execution_count": 13,
				"metadata": {},
				"output_type": "execute_result"
			}],
			"source": [
				"[27*x for x in range(1,20) if x<=10]"
			]
		},
		{
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"Let me add one more loop to make you understand better, "
			]
		},
		{
			"cell_type": "code",
			"execution_count": 14,
			"metadata": {
				"collapsed": false
			},
			"outputs": [{
				"data": {
					"text/plain": [
						"[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]"
					]
				},
				"execution_count": 14,
				"metadata": {},
				"output_type": "execute_result"
			}],
			"source": [
				"[27*z for i in range(50) if i==27 for z in range(1,11)]"
			]
		}, {
			"cell_type": "markdown",
			"metadata": {},
			"source": [
				"This is a customized version of orignal series of Repo https://github.com/rajathkumarmp"
			]
		}
	],
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