Learn Python the Hard Way

Question 1

names for “#”

Answer 1

octothorpe, mesh, hash, pound

Question 2

how to write less than or equal to, more than or equal to

Answer 2

=

Question 3

what does the acronym PEMDAS stand for in math?

Answer 3

the order of operations:
parenthesis
exponents
multiplication
division
addition
subtraction

Question 4

What is the difference between = and == in python?

Answer 4

= assigns the value on the right to the variable on the left. The == tests if both sides have the same value.

Question 5

Which is good python formatting:
x=100
x = 100

Answer 5

x = 100

There should be a space before and after an operator.

Question 6

How do you embed variables in a string?

Answer 6

By using a specialized format sequence and then putting the variables at the end with a special syntax that tells Python “Hey this is a format string. Put these variables in there.”

Question 7

What is the general purpose of a string?

Answer 7

It’s usually something you want to display or “export” out of a program.

Question 8

What is the maximum number of characters you should have in a line of Python code?

Answer 8

80

Question 9

Are single or double quotes better for short strings?

Answer 9

Single quotes are considered better

Question 10

What are the triple quotes (“””) used for?

Answer 10

You can use the triple quotes to enter a long string with newlines.

ex:
"""
Hello
this is
a long
string
"""

Question 11

Why would you use a comma after a print statement?

Answer 11

To avoid creating a newline after that print statement.

Question 12

What is the terminal command for reading python documentation?

Answer 12

pydoc

Question 13

What does the shorthand notation += mean?

Answer 13

It's a contraction of = and +
So:
x = x + y
and 
x += y
are the same

Question 14

Python is called an “object oriented programming language.” What does that mean?

Answer 14

This means there is a construct in Python called a class that lets you structure your software in a particular way. Using classes, you can add consistency to your programs so that they can be used in a cleaner way. At least that’s the theory.

Question 15

What is a class?

Answer 15

A class is a way to take a grouping of functions and data and place them inside a container so you can access them with the . (dot) operator.

Question 16

What is instantiate?

Answer 16

If a class is like a “mini-module,” then there has to be a similar concept to import but for classes. That concept is called “instantiate”, which is just a fancy, obnoxious, overly smart way to say “create.” When you instantiate a class what you get is called an object.

Question 17

define class

Answer 17

Tell Python to make a new type of thing

Question 18

define object

Answer 18

Two meanings:
the most basic type of thing
any instance of some thing

Question 19

define instance

Answer 19

What you get when you tell Python to create a class

Question 20

define def

Answer 20

How you define function inside a class

Question 21

define self

Answer 21

Inside the functions in a class, self is a variable for the instance/object being accessed

Question 22

define inheritance

Answer 22

The concept that one class can inherit traits from another class, much like you and your parents

Question 23

define composition

Answer 23

The concept that a class can be composed of other classes as parts, much like how a car has wheels

Question 24

define attribute

Answer 24

A property classes have that are from composition and are usually variables

Question 25

define is-a

Answer 25

A phrase to say that something inherits from another, as in a "salmon" is-a "fish"

Question 26

define has-a

Answer 26

A phrase to say that something is composed of other things or has a trait, as in " a salmon has-a mouth"

Question 27

``` translate class X(Y) ```

Answer 27

Make a class name X that is-a Y

Question 28

``` translate class X(object): def __init__(self, J) ```

Answer 28

class X has-a __init__ that takes self and J parameters

Question 29

foo = X()

Answer 29

set foo to an instance of class X

Question 30

foo.M(J)

Answer 30

From foo get the M function and call it with parameters self, J

Question 31

foo.K = Q

Answer 31

From foo get the K attribute and set it to Q

Question 32

What is an ordinal number?

Answer 32

They indicate the order of things, like a list of who came in what place in a race.

Question 33

What is a cardinal number?

Answer 33

Cardinal numbers start at 0 and can be accessed randomly without cycling through the numbers before the number you are looking for.

Question 34

How does Zed Shaw feel about Dijkstra?

Answer 34

He recommends you avoid his writings on cardinal numbers unless you enjoy being yelled at by someone who stopped programming at the same time programming started.

Question 35

Should boolean tests in if-statements be complex?

Answer 35

No they should be simple. If they are complex, move their calculations to variables earlier in your function and use a good name for the variable.

Question 36

Does Zed Shaw think you should use a debugger?

Answer 36

Nope. A debugger is like doing a full-body scan on a sick person. You do not get any specific useful information and you find a whole lot of information that doesn't help and is just confusing.

Question 37

define as

Answer 37

Part of the with-as statement | with X as Y: pass

Question 38

define assert

Answer 38

Assert (ensure) that something is true | assert False, "Error!"

Question 39

define from

Answer 39

``` import specific parts of a module import X from Y ```

Question 40

define is

Answer 40

like == to test equality

Question 41

Data Type | None

Answer 41

Represents "nothing" or "no value"

Question 42

Data Type | numbers

Answer 42

Stores only integers

Question 43

Data Type | floats

Answer 43

Stores decimals

Question 44

Data Type | lists

Answer 44

Stores a list of things | j = [1, 2, 3, 4]

Question 45

Data Type | dicts

Answer 45

Stores a key=value mapping of things | {'x': 1, 'y': 2}

Question 46

String formats | %d

Answer 46

Decimal integers (not floating point)

Question 47

String formats | %i

Answer 47

Same as %d

Question 48

String formats | %o

Answer 48

Octal number | "%o" % 1000 == 1750

Question 49

String formats | %r

Answer 49

``` Repr format (debugging format) "%r" % int == "" ```

Question 50

operators | **

Answer 50

power of | 2 ** 4 == 16

Question 51

operators

Answer 51

not equal

Question 52

@

Answer 52

At (decorators) | @classmethod

Question 53

How does Python end up translating mystuff.append('hello')?

Answer 53

append(mystuff, 'hello')

Question 54

Translate | more_stuff.pop()

Answer 54

Call "pop" on "more_stuff" | pop(more_stuff)

Question 55

Translate | pop(more_stuff)

Answer 55

Call "pop" with argument "more_stuff"

Question 56

What is the difference between a fish and a salmon?

Answer 56

A salmon is a kind of fish, but a fish is not a kind of salmon.

Question 57

Mary is a salmon. What is the difference between mary and a salmon?

Answer 57

Mary is a specific instance of a salmon. She was created from some other salmon and now she represents a real thing that has Salmon-like attributes. Fish is a class, salmon is a class, Mary is an object.

Question 58

Is a fish a real thing?

Answer 58

It's a word we attach to instances of things with similar attributes.

Question 59

Is Mary the Salmon a real thing?

Answer 59

Yes it is an instance of Fish, an object, a real thing. Mary is a kind of salmon that is a kind of fish: an object is a class is a class.