Python/String Formatting.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Python String format()\n",
    "[Official docs](https://docs.python.org/3/library/string.html#format-string-syntax)  \n",
    "[more documentation](https://pyformat.info)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Replace with String - positional"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "My name is Alex.\n",
      "My name is Alex Marshall.\n"
     ]
    }
   ],
   "source": [
    "first_name = 'Alex'\n",
    "last_name = 'Marshall'\n",
    "print('My name is {}.'.format(first_name))\n",
    "print('My name is {} {}.'.format(first_name, last_name))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Replace with String using Index\n",
    "Using indexes can be useful when order varies."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "My name is Alex Marshall.\n",
      "My name is Marshall, Alex. First name Alex\n"
     ]
    }
   ],
   "source": [
    "print('My name is {0} {1}.'.format(first_name, last_name))\n",
    "print('My name is {1}, {0}. First name {0}'.format(first_name, last_name))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Alignment: Align Left, Right, Middle\n",
    "{:<} align Left (default is align left, so this is optional)  \n",
    "{:>n} align Right with n padding spaces  \n",
    "{:^n} align Middle with n padding spaces"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Number of cases: 5\n",
      "Number of cases: 16\n",
      "Number of cases: 294\n",
      "Number of cases: 5\n",
      "Number of cases: 16\n",
      "Number of cases: 294\n"
     ]
    }
   ],
   "source": [
    "# align left - these both do the same thing\n",
    "cases = [5, 16, 294]\n",
    "for case in cases:\n",
    "    print('Number of cases: {}'.format(case))\n",
    "for case in cases:\n",
    "    print('Number of cases: {:<}'.format(case))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Number of cases:    5\n",
      "Number of cases:   16\n",
      "Number of cases:  294\n"
     ]
    }
   ],
   "source": [
    "# align right with 5 total spaces\n",
    "for case in cases:\n",
    "    print('Number of cases:{:>5}'.format(case))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Number of cases:  5  \n",
      "Number of cases: 16  \n",
      "Number of cases: 294 \n"
     ]
    }
   ],
   "source": [
    "# align center with 5 total spaces\n",
    "for case in cases:\n",
    "    print('Number of cases:{:^5}'.format(case))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Integers & Floats\n",
    "{:d} Integer variable  \n",
    "{:5d} Integer with padding of 5  \n",
    "{:f} Floating point variable  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Length is 26.\n",
      "Length is     26.\n",
      "In dog years, I'm   8  .\n"
     ]
    }
   ],
   "source": [
    "length = 26\n",
    "print('Length is {:d}.'.format(length))\n",
    "\n",
    "# align right, padding=6, integer\n",
    "print('Length is {:>6d}.'.format(length))\n",
    "\n",
    "# named variable, align center, padding=4, integer\n",
    "print(\"In dog years, I'm {age:^5d}.\".format(age=8))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Distance to moon is 238,900 miles.\n"
     ]
    }
   ],
   "source": [
    "# integer with commas\n",
    "print('Distance to moon is {:,d} miles.'.format(238900))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Radius is 4.780000 inches.\n",
      "Radius is 4.8 inches.\n",
      "Radius is 0004.8 inches.\n",
      "Radius is 4.78000 inches.\n"
     ]
    }
   ],
   "source": [
    "radius = 4.78\n",
    "print('Radius is {:f} inches.'.format(radius))\n",
    "\n",
    "# round to 1 decimal place, float\n",
    "print('Radius is {:.1f} inches.'.format(radius))\n",
    "\n",
    "# padding=6 (pads with leading 0's), round to 1 decimal\n",
    "print('Radius is {:06.1f} inches.'.format(radius))\n",
    "\n",
    "# padding=5 decimal places\n",
    "print('Radius is {:.5f} inches.'.format(radius))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "A is +15.  B is -9.  C is 33.\n",
      "A is +15.  B is   -9.  B is -9.\n"
     ]
    }
   ],
   "source": [
    "# positive & negative signs\n",
    "a, b, c = 15, -9, 33\n",
    "print('A is {:+d}.  B is {:+d}.  C is {:-d}.'.format(a, b, c))\n",
    "\n",
    "# {+3d} shows pos or neg sign, padding=3. \n",
    "# {: d} prints neg or a leading space if positive.\n",
    "print('A is {:+3d}.  B is {:+4d}.  B is {: d}.'.format(a, b, b))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Named Placeholders\n",
    "You can pass in named variables as keyword args, or as an unpacked dict.  \n",
    "And it's easy to pass in a list."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Mekael is a Carpenter.\n"
     ]
    }
   ],
   "source": [
    "print(\"{name} is a {job}.\".format(name='Mekael', job='Carpenter'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "ename": "KeyError",
     "evalue": "'name'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mKeyError\u001b[0m                                  Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-11-be610b0b3133>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0mjob\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0;34m'Carpenter'\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[0;31m# THIS DOES NOT WORK!\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 4\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"{name} is a {job}.\"\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mformat\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mname\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mjob\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mKeyError\u001b[0m: 'name'"
     ]
    }
   ],
   "source": [
    "name = 'Mekael'\n",
    "job = 'Carpenter'\n",
    "# THIS DOES NOT WORK!\n",
    "print(\"{name} is a {job}.\".format(name, job))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Mekael is a Carpenter.\n"
     ]
    }
   ],
   "source": [
    "# This works great\n",
    "print(\"{n} is a {j}.\".format(n=name, j=job))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Mekael is a Carpenter.\n"
     ]
    }
   ],
   "source": [
    "# Or use a dictionary, and ** unpacks the dictionary.\n",
    "jobs = {'name':'Mekael', 'job':'Carpenter'}\n",
    "print(\"{name} is a {job}.\".format(**jobs))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Score 2 is 96\n"
     ]
    }
   ],
   "source": [
    "# passing in a list is clean and easy\n",
    "scores = [78, 96, 83, 86]\n",
    "print('Score 2 is {s[1]}'.format(s = scores))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Scientific Notation\n",
    "Use {:e}, or upper case E."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "My big number is 8.745770e+02\n",
      "A bigger number is 6.022141E+23\n"
     ]
    }
   ],
   "source": [
    "print('My big number is {:e}'.format(874.577))\n",
    "print('A bigger number is {:E}'.format(602214090000000000000000))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Binary & Hexadecimal\n",
    "{:b} converts decimal to binary\n",
    "{:x} converts decimal to hex. Or use upper case X for capitals."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The binary equivalent of 79 is 1001111\n",
      "The Hexadecimal equivalent of 183 is B7\n"
     ]
    }
   ],
   "source": [
    "print('The binary equivalent of 79 is {:b}'.format(79))\n",
    "print('The Hexadecimal equivalent of 183 is {:X}'.format(183))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.7.0"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}