list functions, list as matrix etc..ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### pop()\n",
    "\n",
    "    --> remove() : removes value ... value passed as argument\n",
    "    --> pop() : value at given index is removed ... index passed as argument\n",
    "    --> pop gives error in case of empty list \n",
    "    --> if nothing is mentioned the value removed from last"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "50\n",
      "40\n",
      "[10, 20, 30]\n"
     ]
    }
   ],
   "source": [
    "n=[10,20,30,40,50]\n",
    "print(n.pop())\n",
    "print(n.pop())\n",
    "print(n)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "ename": "IndexError",
     "evalue": "pop from empty list",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-2-f72befbd8481>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[0my\u001b[0m\u001b[1;33m=\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0my\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mpop\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m: pop from empty list"
     ]
    }
   ],
   "source": [
    "y=[]\n",
    "print(y.pop())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3\n",
      "[1, 2, 4, 5, 6, 10, 8]\n"
     ]
    }
   ],
   "source": [
    "n=[1,2,3,4,5,6,10,8]\n",
    "print(n.pop(2))\n",
    "print(n)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "ename": "IndexError",
     "evalue": "pop index out of range",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-4-7d5e6903f961>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mn\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mpop\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m10\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m: pop index out of range"
     ]
    }
   ],
   "source": [
    "print(n.pop(10))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### clear()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 4, 5, 6, 10, 8]\n",
      "[]\n"
     ]
    }
   ],
   "source": [
    "print(n)\n",
    "n.clear()\n",
    "print(n)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### reverse()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[6, 5, 4, 3, 2, 1]\n"
     ]
    }
   ],
   "source": [
    "n=[1,2,3,4,5,6]\n",
    "n.reverse()\n",
    "print(n)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### sort()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 4, 5, 33, 234]\n",
      "[234, 33, 5, 4, 1]\n"
     ]
    }
   ],
   "source": [
    "n=[1,234,33,4,5]\n",
    "n.sort()\n",
    "print(n)\n",
    "n.sort(reverse=True)\n",
    "print(n)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Mathematical operators for list:\n",
    "\n",
    "    + concatenation\n",
    "    * repetition"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4, 5, 6]\n",
      "[1, 2, 3, 1, 2, 3, 1, 2, 3]\n"
     ]
    }
   ],
   "source": [
    "a=[1,2,3]\n",
    "b=[4,5,6]\n",
    "print(a+b)\n",
    "print(a*3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4, 8]\n",
      "[1, 2, 3, 100]\n"
     ]
    }
   ],
   "source": [
    "print(a+[4,8])\n",
    "print(a+[100])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "can only concatenate list (not \"int\") to list",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-11-3fa3a0f3d6c3>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0ma\u001b[0m\u001b[1;33m+\u001b[0m\u001b[1;36m4\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m: can only concatenate list (not \"int\") to list"
     ]
    }
   ],
   "source": [
    "print(a+4)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Comparison operators for list:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "False\n",
      "True\n"
     ]
    }
   ],
   "source": [
    "x=[\"Dog\", \"Cat\",\"Rat\"]\n",
    "y=[\"Dog\", \"Cat\",\"Rat\"]\n",
    "z=[\"DOG\", \"CAT\",\"Rat\"]\n",
    "\n",
    "print(x==y)\n",
    "print(x==z)\n",
    "print(x!=z)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "True\n",
      "False\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "x=[\"dog\", \"Cat\",\"Rat\"]\n",
    "y=[\"Rat\", \"Cat\",\"Dog\"]\n",
    "\n",
    "print(x>y)\n",
    "print(x>=y)\n",
    "print(x<y)\n",
    "print(x<=y)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Membership operators for list:\n",
    "    --> in\n",
    "    --> not in"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "False\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "n=[1,2,3,4,5]\n",
    "print(1 in n)\n",
    "print(4 not in n)\n",
    "print(2 not in n)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### copy()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[10, 20, 30, 40, 50]\n",
      "[10, 20, 100, 40, 50]\n",
      "[10, 20, 30, 40, 50]\n"
     ]
    }
   ],
   "source": [
    "l=[10,20,30,40,50]\n",
    "\n",
    "x=l.copy()\n",
    "x[2]=100\n",
    "print(l)\n",
    "print(x)\n",
    "print(l)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### copy using slicing:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[10, 20, 30, 40, 50]\n",
      "[10, 56, 30, 40, 50]\n",
      "[10, 20, 30, 40, 50]\n"
     ]
    }
   ],
   "source": [
    "a=[10,20,30,40,50]\n",
    "b=a[:]\n",
    "b[1]=56\n",
    "\n",
    "print(a)\n",
    "print(b)\n",
    "print(a)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### wrong way of copying...this would change original list too"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[10, 56, 30, 40, 50]\n",
      "[10, 56, 30, 40, 50]\n",
      "[10, 56, 30, 40, 50]\n"
     ]
    }
   ],
   "source": [
    "a=[10,20,30,40,50]\n",
    "b=a\n",
    "b[1]=56\n",
    "\n",
    "print(a)\n",
    "print(b)\n",
    "print(a)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Nested list:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n",
      "40\n",
      "80\n",
      "200\n"
     ]
    }
   ],
   "source": [
    "n=[10,20 ,30,[40,20],[60,70,80,[100,200]]]\n",
    "print(n[0])\n",
    "print(n[3][0])\n",
    "print(n[4][2])\n",
    "print(n[4][3][1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [
    {
     "ename": "IndexError",
     "evalue": "list index out of range",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-27-569368474160>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mn\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;36m10\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;36m1\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mIndexError\u001b[0m: list index out of range"
     ]
    }
   ],
   "source": [
    "print(n[10][1])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Nested list as matrix:\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1 2 3 \n",
      "4 5 6 \n",
      "7 8 9 \n"
     ]
    }
   ],
   "source": [
    "n=[[1,2,3],[4,5,6],[7,8,9]]\n",
    "\n",
    "for i in n:\n",
    "    for j in i:\n",
    "        print(j, end=\" \")\n",
    "    print()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## List comprehension:\n",
    "\n",
    "#### Syntax: l=[ expression for item in list if condition]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]\n",
      "[2, 4, 8, 16, 32]\n",
      "[1, 9, 25, 49, 81]\n"
     ]
    }
   ],
   "source": [
    "s=[x*x for x in range(1,11)]\n",
    "print(s)\n",
    "\n",
    "v=[2**x for x in range(1,6)]\n",
    "print(v)\n",
    "\n",
    "m=[x for x in s if x%2==1]\n",
    "print(m)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "original matrix: \n",
      "1 2 3 \n",
      "4 5 6 \n",
      "7 8 9 \n",
      "\n",
      "transpose: \n",
      "[1, 4, 7]\n",
      "[2, 5, 8]\n",
      "[3, 6, 9]\n"
     ]
    }
   ],
   "source": [
    "n=[[1,2,3],[4,5,6],[7,8,9]]\n",
    "\n",
    "print(\"original matrix: \")\n",
    "for i in n:\n",
    "    for j in i:\n",
    "        print(j, end=\" \")\n",
    "    print()\n",
    "\n",
    "print(\"\\ntranspose: \")\n",
    "for i in range(len(n[0])):\n",
    "    new=[row[i] for row in n]\n",
    "    print(new)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['a', 'b']\n"
     ]
    }
   ],
   "source": [
    "# wap to print elements with frequency greater than given value of a.\n",
    "\n",
    "l=['a','a','a','a','a','b','b','b','b','c','c','c','d']\n",
    "a=3\n",
    "\n",
    "t=[]\n",
    "for i in l:\n",
    "    if l.count(i)>a and i not in t:\n",
    "        t.append(i)\n",
    "print(t)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": []
  }
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