chapter_4.ipynb

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    "<img src='pyprog.png'>"
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    "## CHAPTER 4 SAMPLE PROGRAMS\n",
    "* Each cell has a Chapter 4 sample program.\n",
    "* Run each cell **as you read the textbook**.\n",
    "* **Experiment!** Edit cells and run them or insert new cells."
   ]
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  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# commission.py\n",
    "# This program calculates sales commissions.\n",
    "\n",
    "# Create a variable to control the loop.\n",
    "keep_going = 'y'\n",
    "\n",
    "# Calculate a series of commissions.\n",
    "while keep_going == 'y':\n",
    "    # Get a salesperson's sales and commission rate.\n",
    "    sales = float(input('Enter the amount of sales: '))\n",
    "    comm_rate = float(input('Enter the commission rate: '))\n",
    "\n",
    "    # Calculate the commission.\n",
    "    commission = sales * comm_rate\n",
    "\n",
    "    # Display the commission.\n",
    "    print('The commission is $', \\\n",
    "          format(commission, ',.2f'), sep='')\n",
    "\n",
    "    # See if the user wants to do another one.\n",
    "    keep_going = input('Do you want to calculate another ' + \\\n",
    "                       'commission (Enter y for yes): ')"
   ]
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  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# temperature.py\n",
    "# This program assists a technician in the process\n",
    "# of checking a substance's temperature.\n",
    "\n",
    "# Create a variable to represent the maximum\n",
    "# temperature.\n",
    "max_temp = 102.5\n",
    "\n",
    "# Get the substance's temperature.\n",
    "temperature = float(input(\"Enter the substance's Celsius temperature: \"))\n",
    "\n",
    "# As long as necessary, instruct the user to\n",
    "# adjust the thermostat.\n",
    "while temperature > max_temp:\n",
    "    print('The temperature is too high.')\n",
    "    print('Turn the thermostat down and wait')\n",
    "    print('5 minutes. Then take the temperature')\n",
    "    print('again and enter it.')\n",
    "    temperature = float(input('Enter the new Celsius temperature: '))\n",
    "\n",
    "# Remind the user to check the temperature again\n",
    "# in 15 minutes.\n",
    "print('The temperature is acceptable.')\n",
    "print('Check it again in 15 minutes.')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# infinite.py\n",
    "# This program demonstrates an infinite loop.\n",
    "# Create a variable to control the loop.\n",
    "keep_going = 'y'\n",
    "\n",
    "# Warning! Infinite loop!\n",
    "while keep_going == 'y':\n",
    "    # Get a salesperson's sales and commission rate.\n",
    "    sales = float(input('Enter the amount of sales: '))\n",
    "    comm_rate = float(input('Enter the commission rate: '))\n",
    "\n",
    "    # Calculate the commission.\n",
    "    commission = sales * comm_rate\n",
    "\n",
    "    # Display the commission.\n",
    "    print('The commission is $', \\\n",
    "          format(commission, ',.2f'), sep='')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
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   "source": [
    "# simple_loop1.py\n",
    "# This program demonstrates a simple for loop\n",
    "# that uses a list of numbers.\n",
    "\n",
    "print('I will display the numbers 1 through 5.')\n",
    "for num in [1, 2, 3, 4, 5]:\n",
    "    print(num)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# simple_loop2.py\n",
    "# This program also demonstrates a simple for\n",
    "# loop that uses a list of numbers.\n",
    "\n",
    "print('I will display the odd numbers 1 through 9.')\n",
    "for num in [1, 3, 5, 7, 9]:\n",
    "    print(num)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# simple_loop3.py\n",
    "# This program also demonstrates a simple for\n",
    "# loop that uses a list of strings.\n",
    "\n",
    "for name in ['Winken', 'Blinken', 'Nod']:\n",
    "    print(name)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# simple_loop4.py\n",
    "# This program demonstrates how the range\n",
    "# function can be used with a for loop.\n",
    "\n",
    "# Print a message five times.\n",
    "for x in range(5):\n",
    "    print('Hello world!')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# squares.py\n",
    "# This program uses a loop to display a\n",
    "# table showing the numbers 1 through 10\n",
    "# and their squares.\n",
    "\n",
    "# Print the table headings.\n",
    "print('Number\\tSquare')\n",
    "print('--------------')\n",
    "\n",
    "# Print the numbers 1 through 10\n",
    "# and their squares.\n",
    "for number in range(1, 11):\n",
    "    square = number**2\n",
    "    print(number, '\\t', square)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
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   "source": [
    "# speed_converter.py\n",
    "# This program converts the speeds 60 kph\n",
    "# through 130 kph (in 10 kph increments)\n",
    "# to mph.\n",
    "\n",
    "start_speed = 60            # Starting speed\n",
    "end_speed = 131             # Ending speed\n",
    "increment = 10              # Speed increment\n",
    "conversion_factor = 0.6214  # Conversion factor\n",
    "\n",
    "# Print the table headings.\n",
    "print('KPH\\tMPH')\n",
    "print('--------------')\n",
    "\n",
    "# Print the speeds.\n",
    "for kph in range(start_speed, end_speed, increment):\n",
    "    mph = kph * conversion_factor\n",
    "    print(kph, '\\t', format(mph, '.1f'))"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# user_squares1.py\n",
    "# This program uses a loop to display a\n",
    "# table of numbers and their squares.\n",
    "\n",
    "# Get the ending limit.\n",
    "print('This program displays a list of numbers')\n",
    "print('(starting at 1) and their squares.')\n",
    "end = int(input('How high should I go? '))\n",
    "    \n",
    "# Print the table headings.\n",
    "print()\n",
    "print('Number\\tSquare')\n",
    "print('--------------')\n",
    "\n",
    "# Print the numbers and their squares.\n",
    "for number in range(1, end + 1):\n",
    "    square = number**2\n",
    "    print(number, '\\t', square)"
   ]
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   "cell_type": "code",
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   "source": [
    "# user_squares2.py\n",
    "# This program uses a loop to display a\n",
    "# table of numbers and their squares.\n",
    "\n",
    "# Get the starting value.\n",
    "print('This program displays a list of numbers')\n",
    "print('and their squares.')\n",
    "start = int(input('Enter the starting number: '))\n",
    "\n",
    "# Get the ending limit.\n",
    "end = int(input('How high should I go? '))\n",
    "   \n",
    "# Print the table headings.\n",
    "print()\n",
    "print('Number\\tSquare')\n",
    "print('--------------')\n",
    "\n",
    "# Print the numbers and their squares.\n",
    "for number in range(start, end + 1):\n",
    "    square = number**2\n",
    "    print(number, '\\t', square)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# sum_numbers.py\n",
    "# This program calculates the sum of a series\n",
    "# of numbers entered by the user.\n",
    "\n",
    "max = 5   # The maximum number\n",
    "\n",
    "# Initialize an accumulator variable.\n",
    "total = 0.0\n",
    "   \n",
    "# Explain what we are doing.\n",
    "print('This program calculates the sum of')\n",
    "print(max, 'numbers you will enter.')\n",
    "\n",
    "# Get the numbers and accumulate them.\n",
    "for counter in range(max):\n",
    "    number = int(input('Enter a number: '))\n",
    "    total = total + number\n",
    "\n",
    "# Display the total of the numbers.\n",
    "print('The total is', total)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# property_tax.py\n",
    "# This program displays property taxes.\n",
    "\n",
    "TAX_FACTOR = 0.0065   # Represents the tax factor.\n",
    "\n",
    "# Get the first lot number.\n",
    "print('Enter the property lot number')\n",
    "print('or enter 0 to end.')\n",
    "lot = int(input('Lot number: '))\n",
    "\n",
    "# Continue processing as long as the user\n",
    "# does not enter lot number 0.\n",
    "while lot != 0:\n",
    "    # Get the property value.\n",
    "    value = float(input('Enter the property value: '))\n",
    "\n",
    "    # Calculate the property's tax.\n",
    "    tax = value * TAX_FACTOR\n",
    "\n",
    "    # Display the tax.\n",
    "    print('Property tax: $', format(tax, ',.2f'), sep='')\n",
    "\n",
    "    # Get the next lot number.\n",
    "    print('Enter the next lot number or')\n",
    "    print('enter 0 to end.')\n",
    "    lot = int(input('Lot number: '))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "# gross_pay.py\n",
    "# This program displays gross pay.\n",
    "# Get the number of hours worked.\n",
    "hours = int(input('Enter the hours worked this week: '))\n",
    "\n",
    "# Get the hourly pay rate.\n",
    "pay_rate = float(input('Enter the hourly pay rate: '))\n",
    "\n",
    "# Calculate the gross pay.\n",
    "gross_pay = hours * pay_rate\n",
    "\n",
    "# Display the gross pay.\n",
    "print('Gross pay: $', format(gross_pay, ',.2f'))"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# retail_no_validation.py\n",
    "# This program calculates retail prices.\n",
    "\n",
    "mark_up = 2.5  # The markup percentage\n",
    "another = 'y'  # Variable to control the loop.\n",
    "\n",
    "# Process one or more items.\n",
    "while another == 'y' or another == 'Y':\n",
    "    # Get the item's wholesale cost.\n",
    "    wholesale = float(input(\"Enter the item's \" + \\\n",
    "                            \"wholesale cost: \"))\n",
    "\n",
    "    # Calculate the retail price.\n",
    "    retail = wholesale * mark_up\n",
    "\n",
    "    # Display the retail price.\n",
    "    print('Retail price: $', format(retail, ',.2f'), sep='')\n",
    "\n",
    "\n",
    "    # Do this again?\n",
    "    another = input('Do you have another item? ' + \\\n",
    "                    '(Enter y for yes): ')"
   ]
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# retail_with_validation.py\n",
    "# This program calculates retail prices.\n",
    "\n",
    "mark_up = 2.5  # The markup percentage\n",
    "another = 'y'  # Variable to control the loop.\n",
    "\n",
    "# Process one or more items.\n",
    "while another == 'y' or another == 'Y':\n",
    "    # Get the item's wholesale cost.\n",
    "    wholesale = float(input(\"Enter the item's \" + \\\n",
    "                            \"wholesale cost: \"))\n",
    "\n",
    "    # Validate the wholesale cost.\n",
    "    while wholesale < 0:\n",
    "        print('ERROR: the cost cannot be negative.')\n",
    "        wholesale = float(input('Enter the correct ' + \\\n",
    "                                'wholesale cost:'))\n",
    "\n",
    "    # Calculate the retail price.\n",
    "    retail = wholesale * mark_up\n",
    "\n",
    "    # Display the retail price.\n",
    "    print('Retail price: $', format(retail, ',.2f'))\n",
    "\n",
    "\n",
    "    # Do this again?\n",
    "    another = input('Do you have another item? ' + \\\n",
    "                    '(Enter y for yes): ')"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# test_score_averages.py\n",
    "# This program averages test scores. It asks the user for the\n",
    "# number of students and the number of test scores per student.\n",
    "\n",
    "# Get the number of students.\n",
    "num_students = int(input('How many students do you have? '))\n",
    "\n",
    "# Get the number of test scores per student.\n",
    "num_test_scores = int(input('How many test scores per student? '))\n",
    "\n",
    "# Determine each students average test score.\n",
    "for student in range(num_students):\n",
    "    # Initialize an accumulator for test scores.\n",
    "    total = 0.0\n",
    "    # Get a student's test scores.\n",
    "    print('Student number', student + 1)\n",
    "    print('-----------------')\n",
    "    for test_num in range(num_test_scores):\n",
    "        print('Test number', test_num + 1, end='')\n",
    "        score = float(input(': '))\n",
    "        # Add the score to the accumulator.\n",
    "        total += score\n",
    "\n",
    "    # Calculate the average test score for this student.\n",
    "    average = total / num_test_scores\n",
    "\n",
    "    # Display the average.\n",
    "    print('The average for student number', student + 1, \\\n",
    "          'is:', format(average, '.1f'))\n",
    "    print()"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# rectangular_pattern.py\n",
    "# This program displays a rectangular pattern\n",
    "# of asterisks.\n",
    "rows = int(input('How many rows? '))\n",
    "cols = int(input('How many columns? '))\n",
    "\n",
    "for r in range(rows):\n",
    "    for c in range(cols):\n",
    "        print('*', end='')\n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# triangle_pattern.py\n",
    "# This program displays a triangle pattern.\n",
    "base_size = 8\n",
    "\n",
    "for r in range(base_size):\n",
    "    for c in range(r + 1):\n",
    "        print('*', end='')\n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# stair_step_pattern.py\n",
    "# This program displays a stair-step pattern.\n",
    "num_steps = 6\n",
    "\n",
    "for r in range(num_steps):\n",
    "   for c in range(r):\n",
    "      print(' ', end='')\n",
    "   print('#')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The programs below crash on this server.\n",
    "* Copy-paste each into an IDLE **script window** to run."
   ]
  },
  {
   "cell_type": "code",
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   "outputs": [],
   "source": [
    "# concentric_circles.py\n",
    "\n",
    "# Concentric circles\n",
    "import turtle\n",
    "\n",
    "# Named constants\n",
    "NUM_CIRCLES = 20\n",
    "STARTING_RADIUS = 20\n",
    "OFFSET = 10\n",
    "ANIMATION_SPEED = 0\n",
    "\n",
    "# Setup the turtle.\n",
    "turtle.speed(ANIMATION_SPEED)\n",
    "turtle.hideturtle()\n",
    "\n",
    "# Set the radius of the first circle\n",
    "radius = STARTING_RADIUS\n",
    "\n",
    "# Draw the circles.\n",
    "for count in range(NUM_CIRCLES):\n",
    "    # Draw the circle.\n",
    "    turtle.circle(radius)\n",
    "\n",
    "    # Get the coordinates for the next circle.\n",
    "    x = turtle.xcor()\n",
    "    y = turtle.ycor() - OFFSET\n",
    "\n",
    "    # Calculate the radius for the next circle.\n",
    "    radius = radius + OFFSET\n",
    "\n",
    "    # Position the turtle for the next circle.\n",
    "    turtle.penup()\n",
    "    turtle.goto(x, y)\n",
    "    turtle.pendown()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# spiral_circles.py\n",
    "\n",
    "# This program draws a design using repeated circles.\n",
    "import turtle\n",
    "\n",
    "# Named constants\n",
    "NUM_CIRCLES = 36    # Number of circles to draw\n",
    "RADIUS = 100        # Radius of each circle\n",
    "ANGLE = 10          # Angle to turn\n",
    "ANIMATION_SPEED = 0 # Animation speed\n",
    "\n",
    "# Set the animation speed.\n",
    "turtle.speed(ANIMATION_SPEED)\n",
    "\n",
    "# Draw 36 circles, with the turtle tilted\n",
    "# by 10 degrees after each circle is drawn.\n",
    "for x in range(NUM_CIRCLES):\n",
    "    turtle.circle(RADIUS)\n",
    "    turtle.left(ANGLE)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# spiral_lines.py\n",
    "\n",
    "# This program draws a design using repeated lines.\n",
    "import turtle\n",
    "\n",
    "# Named constants\n",
    "START_X = -200      # Starting X coordinate\n",
    "START_Y = 0         # Starting Y coordinate\n",
    "NUM_LINES = 36      # Number of lines to draw\n",
    "LINE_LENGTH = 400   # Length of each line\n",
    "ANGLE = 170         # Angle to turn\n",
    "ANIMATION_SPEED = 0 # Animation speed\n",
    "\n",
    "# Move the turtle to its initial position.\n",
    "turtle.hideturtle()\n",
    "turtle.penup()\n",
    "turtle.goto(START_X, START_Y)\n",
    "turtle.pendown()\n",
    "\n",
    "# Set the animation speed.\n",
    "turtle.speed(ANIMATION_SPEED)\n",
    "\n",
    "# Draw 36 lines, with the turtle tilted\n",
    "# by 170 degrees after each line is drawn.\n",
    "for x in range(NUM_LINES):\n",
    "    turtle.forward(LINE_LENGTH)\n",
    "    turtle.left(ANGLE)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Now try some end-of-chapter Programming Exercises."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
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