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Practice: The Basics

Practice: The Basics#

With variables, conditionals and operators under your belt, this chapter is meant to give you additional practice. Note that each question will include a handful of assert statements. After you write and execute the code to each question, each assert should “pass silently” (meaning: should give no output upon execution) indicating that you are on the right track. After you’ve written your code and run the asserts, you can always check your answers, as the answers to these questions are included in the “Answers” chapter of this book.

Variables#

Variables Q1. Write five lines of code that define five different variables named var_float, var_str, and var_bool, var_tuple, and var_dict, storing a float, a string, and a boolean, a tuple, and a dictionary, respectively. (You get to choose the specific float, string, boolean, tuple, or dictionary each variable stores.)

Checks you can use to see if you’re on the right track:

assert isinstance(var_float, float)
assert isinstance(var_str, str)
assert isinstance(var_bool, bool)
assert isinstance(var_tuple, tuple)
assert isinstance(var_dict, dict)

Variables Q2. Consider each of the following scenarios and determine what type of collection (list, tuple, dictionary) would be best to use. For each scenario, store ‘list’, ‘tuple’ or ‘dictionary’ in the variable specified, depending upon which is best for the given scnenario. (Note: Capitalization and spelling matter.)

For example, for scenario_A, if you thought the correct answer were ‘list’ your answer in the answer cell would be:

scenario_A = 'list'

Scenarios:

  • scenario_A | You want to store all of the names of the films that won an Academy Award last year.

  • scenario_B | You want to keep a record of all the email addresses (and only the email addresses) of all of Directors working in Hollywood, so that you can email them your brilliant ideas whenever you have them.

  • scenario_C | You want to store the names and email addresses of all of the Directors working in Hollywood, so that you can email them your brilliant ideas whenever you have them and address the email to the right name.

  • scenario_D | You want to keep a record of all of the films that have ever won an Academy award and the year in which that award was won.

Checks you can use to see if you’re on the right track:

assert scenario_A in ['tuple', 'list', 'dictionary']
assert scenario_B in ['tuple', 'list', 'dictionary']
assert scenario_C in ['tuple', 'list', 'dictionary']
assert scenario_D in ['tuple', 'list', 'dictionary']

Operators#

Operators Q1 Use the variables provided below (var_low, var_mid and var_high) to generate the variables: var_even and var_odd according to the following specifications:

  • var_even | use the 3 variables provided once each and at least two of the math operators (+, -, *, /, **, //, %) to store the value 12

  • var_odd | use the 3 variables provided once each and at least two of the math operators (+, -, *, /, **, //, %) to store the value 13

Variables provided:

var_low = 2
var_mid = 20
var_high = 30

Checks you can use to see if you’re on the right track:

assert int(var_even % 2) == 0
assert var_even == 12
assert var_odd % 2 != 0
assert var_odd == 13

Operators Q2. First, define two variables below: my_age and pres_age. Store your age (as an integer) in my_age and store the current US President’s age (as an integer) in pres_age.

Then, use (refer to) my_age and pres_age to define define two variables: true_compar and false_compar.

These variables must satisfy the following requirements:

  1. Each variable must be defined using one comparison operator (<,>,<=,>=,!=,==).

  2. Each variable must use and refer to my_age and pres_age (and no other values or variables)

  3. true_compar should evaluate as the boolean True; false_compar should evaluate as the boolean False

Checks you can use to see if you’re on the right track:

assert isinstance(my_age, int)
assert my_age < 150
assert pres_age <150
assert true_compar
assert not false_compar

Operators Q3. Two variables (spring_holidays and current_holidays) have been created for you below. Using only these two variables and membership operators, define the following two variables below (yes_member and no_member), such that they meet the following specifications:

  • yes_member | stores the boolean True

  • no_member | stores the boolean False

Variables provided:

spring_holidays = ['César Chávez', 'Passover', 'Easter', 
                   'Ramadan', 'Shavout', 'Memorial Day']
current_holiday = 'Ramadan'

Checks you can use to see if you’re on the right track:

assert yes_member
assert not no_member

Operators Q4. Create three variables: var_even, var_odd, and var_operator.

Across these three variables:

  • all seven math operators (+, -, /, *, **, %, //) must be used at least once

  • var_even must store an even number

  • var_odd must store an odd number

  • var_operator can include other variables/numbers but must use (refer to) the variables var_even and var_odd during assignment and must store (have the value) 6 (or 6.0)

Checks you can use to see if you’re on the right track:

assert var_odd % 2 != 0
assert int(var_even % 2) == 0
assert isinstance(var_operator, float) or isinstance(var_operator, int)
assert var_operator == 6

Operators Q5. Your answer will define two variables: true_var and false_var.

These variables must satisfy the following requirements:

  1. Each variable must be defined using at least one comparison operator (<,>,<=,>=,!=,==).

  2. Each variable must use and refer to at least one variables defined below (var_low, var_mid, var_high)

  3. Additional values and/or operators may also be used, but true_var must use the or operator; false_var must use the and operator.

  4. true_var should evaluate as the boolean True; false_var should evaluate as the boolean False

Variables provided:

var_low = 35 % 11
var_mid = 5 ** 2
var_high = (14 + 2) * 6

Checks you can use to see if you’re on the right track:

assert true_var
assert not false_var

Operators Q6 Create three variables: comp_a, comp_b, and comp_c.

These variables must satisfy the following requirements:

  1. Each variable must store (aka return) the Boolean True

  2. Additional operators may also be used, but comp_a must use the and operator; comp_b must use the or operator, and comp_c must use the not operator.

  3. Each variable must be created using at least two of the comparison operators (<,>,<=,>=,!=,==).

  4. All six comparison operators must show up in the cell below at least once.

Checks you can use to see if you’re on the right track:

assert comp_a
assert comp_b
assert comp_c

Operators Q7. Using the following string and list provided below, create two variables memb_a and memb_b that satisfy the following conditions:

  1. memb_a must use the in operator to check membership in my_string. It should store (return) True.

  2. memb_b must use the not in operator to check membership in my_list. It should store (return) False.

  3. memb_a must refer to the my_string variable defined for you below. memb_b must refer to the my_list variable defined for you below.

Variables provided:

my_string = 'I love Python!'
my_list = ['Chapters', 'Exercises', 'Practice']

Checks you can use to see if you’re on the right track:

assert memb_a
assert not memb_b

Conditionals#

Conditionals Q1. Store your first name as a string in the variable my_name.

Write a conditional that will determine if there are more letters in your name (my_name) relative to the number of letters in the comparison_name (provided below, and storing the string ‘Shannon’).

If your name is:

  • shorter than the comparison_name, store the string ‘shorter’ in the variable output

  • longer than the comparison_name, store the string ‘longer’ in the variable output

  • the same length as comparison_name, store the string ‘same length’ in the variable output

Note: Do not hard-code. This means your code should work (store the correct string in output) regardless of the specific strings stored in comparison_name or my_name.

Variable provided:

comparison_name = 'Shannon'

Checks you can use to see if you’re on the right track:

assert my_name
assert output
assert output in ['shorter', 'longer', 'same length']

Topics Synthesis#

Synthesis Q1. Create two variables: var_cat and var_sum.

  • var_cat should store a string created (assigned) by concatenating two strings together

  • var_sum should store a numeric variable (float or int) created (assigned) by adding two numeric values together

The specific values you use to generate var_cat and var_sum are up to you, as long as they fulfull the criteria specified.

Checks you can use to see if you’re on the right track:

assert isinstance(var_cat, str)
assert isinstance(var_sum, float) or isinstance(var_sum, int)

Synthesis Q2. Create three variables: var_int, var_float, and var_combined.

  • var_int should store an integer

  • var_float should store a float

  • var_combined should use a math operator to add var_int and var_float together

The specific values you use to generate var_int and var_float are up to you, as long as they fulfull the criteria specified.

Checks you can use to see if you’re on the right track:

assert isinstance(var_int, int)
assert isinstance(var_float, float)
assert var_combined == var_int + var_float

Synthesis Q3. create three variables: var_a, var_b, and var_c.

These variables must satisfy the following requirements:

  1. var_a must store a float (you get to choose the specific float)

  2. var_b must use at least two of the comparison operators (<,>,<=,>=,!=,==) and store (return) the value True.

  3. var_c must use at least two of the math operators (+, -, /, *, **, %, //) and store the value 36

Checks you can use to see if you’re on the right track:

assert isinstance(var_a, float)
assert var_b 
assert var_c == 36

Synthesis Q4. create three variables: var_a, var_b, and var_c.

  • var_a should store four characters in an immutable variable type that is only able to store one piece of information

  • var_b should be a single value that, when added to itself returns a whole number

  • var_c should be an immutable variable storing three different values

The specific values you use to generate the variables are up to you, as long as they fulfull the criteria specified.

Checks you can use to see if you’re on the right track:

assert isinstance(var_a, str)
assert len(var_a) == 4
assert var_b % 1 == 0 
assert isinstance(var_c, tuple)
assert len(var_c) == 3
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