Chapter 5 - ForLoops.ipynb

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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Python - For Loops"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In the context of most data science work, Python for loops are used to loop through an iterable object (like a list, tuple, set, etc.) and perform the same action for each entry. For example, a for loop would allow us to iterate through a list, performing the same action on each item in the list.\n",
    "\n",
    "(An interable object, by the way, is any Python object we can iterate through, or “loop” through, and return a single element at a time. Lists, for example, are iterable and return a single list entry at a time, in the order entries are listed. Strings are iterable and return one character at a time, in the order the characters appear. Etc.)"
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You create a for loop by first defining the iterable object you’d like to loop through, and then defining the actions you’d like to perform on each item in that iterable object. For example, when iterating through a list, you first specify the list you’d like to iterate through, and then specify what action you’d like to perform on each list item."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "assets = ['BTC', 'ETH', 'SOL', 'LUNA', 'OHM']\n",
    "for asset in assets:\n",
    "    print(asset)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Strings"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Even strings are iterable objects, they contain a sequence of characters:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_string = 'bitcoin'\n",
    "for s in my_string: \n",
    "    print(s)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The break statement"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "The break statement allows us to exit the loop before the code loops through all the items:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for asset in assets:\n",
    "    if asset == 'SOL':\n",
    "        break\n",
    "    else:\n",
    "        print(asset)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The continue statement"
   ]
  },
  {
   "cell_type": "markdown",
   "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": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for asset in assets:\n",
    "    if asset == 'SOL':\n",
    "        continue\n",
    "    else:\n",
    "        print(asset)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The range() function"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can generate a sequence of numbers using **range()** function. range(10) will generate numbers from 0 to 9 (10 numbers).\n",
    "\n",
    "We can also define the start, stop and step size as range(start, stop,step_size). step_size defaults to 1 if not provided."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(list(range(10)))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can use the range() function in for loops to iterate through a sequence of numbers. It can be combined with the len() function to iterate through a sequence using indexing. Here is an example."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in range(len(assets)):\n",
    "    print(\"My biggest bag is\", assets[i])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Exercises"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Write a program that appends the square of each number to a new list."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Write your code below\n",
    "numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
    "squared_numbers = []"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Write a program to display only those numbers from a list that satisfy the following conditions\n",
    "\n",
    "* The number must be divisible by five (google modulo)\n",
    "* If the number is greater than 150, then skip it and move to the next number\n",
    "* If the number is greater than 500, then stop the loop\n",
    "\n",
    "Expected **output**: \n",
    "\n",
    "75\n",
    "150\n",
    "145"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Write your code below\n",
    "numbers = [12, 75, 150, 180, 145, 525, 50]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Using a for loop and if statement, append the value minus 1000 for each key to the new list if the value is above 1000. i.e.: if the value is 1500, 500 should be added to the new list."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "dictionary = {\"z1\":900, \"t1\": 1100, \"p1\": 2300, \"r1\": 1050, \"k1\": 3200, \"g1\": 400}\n",
    "new_values = []\n",
    "\n",
    "# Type your answer here.\n",
    "\n",
    "print(new_values)"
   ]
  }
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