Chapter 2 - DataTypes&Variables.ipynb

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  {
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   "metadata": {},
   "source": [
    "# Python - Variables and Data Types"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Variables are nothing but reserved memory locations to store values. This means that when you create a variable you reserve some space in memory."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Assigning Values to Variables\n",
    "Python variables do not need explicit declaration to reserve memory space. The declaration happens automatically when you assign a value to a variable. The equal sign (**=**) is used to assign values to variables.\n",
    "\n",
    "The operand to the left of the = operator is the name of the variable and the operand to the right of the = operator is the value stored in the variable. For example −"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "ticker = 'BTC'\n",
    "price = 10"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Standard Data Types\n",
    "\n",
    "The data stored in memory can be of many types. For example, a person's age is stored as a numeric value and his or her address is stored as alphanumeric characters. Python has various standard data types that are used to define the operations possible on them and the storage method for each of them."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Python has five standard data types −\n",
    "\n",
    "* Numbers\n",
    "* String\n",
    "* List\n",
    "* Tuple\n",
    "* Dictionary"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Python Numbers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Number data types store numeric values. Number objects are created when you assign a value to them. For example −"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "var1 = 1\n",
    "var2 = 10"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Python also supports floats (floating point real values) which basically means decimals. For example -"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "decimal1 = 1.1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Python Strings"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Strings in Python are identified as a contiguous set of characters represented in the quotation marks. Python allows for either pairs of single or double quotes."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_string = 'This is a string in Python'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "String are awesome. You can do all  sorts of things with them. For example, subsets of strings can be taken using the slice operator ([ ] and [:] ) with indexes starting at 0 in the beginning of the string and working their way from -1 at the end. If we wanted to get only the word **This** from the above string, we could do it like this:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'This'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_string[:4]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "String are considered objects in Python. This means they come equipped with **methods** which can be accessed using the the dot (.) operator. Here are a few examples of the kinds of methods strings have:\n",
    "\n",
    "* .upper()\n",
    "* .lower()\n",
    "* .title()\n",
    "* .count() (count how many times a character is included in a string)\n",
    "* .replace() (replace character with another character)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_new_string = 'I love Python'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To call a method from a string you simply need to use the . operators on the string variable like this:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'I LOVE PYTHON'"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "upper_case_string = my_new_string.upper()\n",
    "upper_case_string"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'i love python'"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "lower_case_string = my_new_string.lower()\n",
    "lower_case_string"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'I Love Python'"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "title_string = my_new_string.title()\n",
    "title_string"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_new_string.count('o')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'I luve Pythun'"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "replaced_string = my_new_string.replace('o', 'u')\n",
    "replaced_string"
   ]
  }
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