16_python_forloops.ipynb

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  {
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   "source": [
    "# Python For Loops"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b86cbf8f",
   "metadata": {},
   "source": [
    "A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string).\n",
    "\n",
    "This is less like the for keyword in other programming languages, and works more like an iterator method as found in other object-orientated programming languages.\n",
    "\n",
    "With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "29a0bff2",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "apple\n",
      "orange\n",
      "berry\n",
      "cherry\n"
     ]
    }
   ],
   "source": [
    "fruits = [\"apple\", \"orange\",\"berry\", \"cherry\"]\n",
    "for x in fruits:\n",
    "  print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5b6e6a79",
   "metadata": {},
   "source": [
    "# Looping Through a String"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6928bc63",
   "metadata": {},
   "source": [
    "Even strings are iterable objects, they contain a sequence of characters:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "c96a73e4",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "a\n",
      "p\n",
      "p\n",
      "l\n",
      "e\n"
     ]
    }
   ],
   "source": [
    "for x in \"apple\":\n",
    "  print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5578d94f",
   "metadata": {},
   "source": [
    "# The break Statement"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e4b44b82",
   "metadata": {},
   "source": [
    "With the break statement we can stop the loop before it has looped through all the items:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "12867007",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "apple\n"
     ]
    }
   ],
   "source": [
    "fruits = [\"apple\", \"orange\",\"berry\",\"cherry\"]\n",
    "for x in fruits:\n",
    "  print(x)\n",
    "  if x == \"apple\":\n",
    "    break"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7c8d0135",
   "metadata": {},
   "source": [
    "# The continue Statement"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "3d31ad6c",
   "metadata": {},
   "source": [
    "With the continue statement we can stop the current iteration of the loop, and continue with the next:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "76551f9a",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "orange\n",
      "berry\n",
      "cherry\n"
     ]
    }
   ],
   "source": [
    "fruits = [\"apple\", \"orange\",\"berry\",\"cherry\"]\n",
    "for x in fruits:\n",
    "  if x == \"apple\": #continue statement we can stop the current iteration of the loop, and continue with the next.\n",
    "    continue\n",
    "  print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b5d4d400",
   "metadata": {},
   "source": [
    "# The range() Function"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "70501e60",
   "metadata": {},
   "source": [
    "To loop through a set of code a specified number of times, we can use the range() function,\n",
    "The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "46274ef7",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n"
     ]
    }
   ],
   "source": [
    "for x in range(10):  #To loop through a set of code a specified number of times, we can use the range() function,\n",
    "                     #The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.\n",
    "  print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "18bbc3ce",
   "metadata": {},
   "source": [
    "# Else in For Loop"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d7cbdb10",
   "metadata": {},
   "source": [
    "The else keyword in a for loop specifies a block of code to be executed when the loop is finished:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "21066aea",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n",
      "nothing\n"
     ]
    }
   ],
   "source": [
    "for x in range(10):\n",
    "  print(x)    #else keyword in a for loop specifies a block of code to be executed when the loop is finished.\n",
    "else:\n",
    "  print(\"nothing\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2014ab2a",
   "metadata": {},
   "source": [
    "# Nested Loops"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "51bcee3b",
   "metadata": {},
   "source": [
    "A nested loop is a loop inside a loop.\n",
    "\n",
    "The \"inner loop\" will be executed one time for each iteration of the \"outer loop\":"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "c9b4b3cd",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "red apple\n",
      "red orange\n",
      "red cherry\n",
      "big apple\n",
      "big orange\n",
      "big cherry\n",
      "tasty apple\n",
      "tasty orange\n",
      "tasty cherry\n"
     ]
    }
   ],
   "source": [
    "t= [\"red\", \"big\", \"tasty\"]\n",
    "fruits = [\"apple\", \"orange\", \"cherry\"]\n",
    "\n",
    "for x in t:     #A nested loop is a loop inside a loop.\n",
    "\n",
    "                    #The \"inner loop\" will be executed one time for each iteration of the \"outer loop\"\n",
    " for y in fruits:\n",
    "    print(x, y)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "c40ac75b",
   "metadata": {},
   "source": [
    "# The pass Statement"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "419d1d00",
   "metadata": {},
   "source": [
    "for loops cannot be empty, but if you for some reason have a for loop with no content, put in the pass statement to avoid getting an error."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "f2e06ff9",
   "metadata": {},
   "outputs": [],
   "source": [
    "for x in [0, 1, 2,3,4,5,6,7,8,9,10]:\n",
    "  pass             #for loops cannot be empty, but if you for some reason have a for loop with no content, put in the pass statement to avoid getting an error."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "b42b68de",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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