Python Basics: Dictionaries and Strings

How to define an empty dictionary?

• my_dict = {}

• my_dict = empty_dict()

• my_dict = []

• my_dict = ()

Answer explanation

There are two ways to define an empty dictionary:

* my_dict = {}

* my_dict = dict()

Tags

Dictionaries

How to define a dictionary with one person (name) and its age?

• ages = {"Abraham"=1000}

• ages = ["Abraham": 1000]

• ages = {"Abraham": 1000}

• ages = ["Abraham"=1000]

Answer explanation

Curly brackets {...} for a dictionary and : to match a key to its value

Tags

Dictionaries

How to access the value matching a key "China" in a dictionary countries?

• countries{"China"}

• countries["China"]

• countries("China")

• countries.China

Answer explanation

To access a value, we always use [...], shall it be in lists, strings (character or slice), tuples, or dictionaries

Tags

Dictionaries

What does the following do:

_{my_dictionary = {"one":1, "two:2}}

_{my_dictionary["one"] = 111}

• Replace the value of "one" with 111

• Nothing because we already have a value "one"

• Store a second value "one" with value 111

• Raise an Error

Answer explanation

In a dictionary, the keys are unique, and we have a matching value for each.

Setting a new value will replace the previous one (because there is a simple way to set a value only if it does not exist).

Tags

Dictionaries

How to check a dictionary my_dict has a certain key my_key?

• my_key in my_dict

• my_dict.has(my_key)

• my_dict has my_key

• my_dict in my_key

Answer explanation

The keyword in is used:

* To loop in "for loops"

* To check if an element is part of a list, string, or dictionary

Tags

Dictionaries

What does the split method do (e.g. my_string.strip(...))?

• Return a string with all spaces removed, even in the middle

• Return a string with all spaces at the beginning and end removed

• Return a list of strings (my_string being cut into slices)

• Modify my_string by removing spaces and return nothing

Answer explanation

The methods on the string (like .strip() or .split(), etc.) does not change the initial string but return a modified one.

Tags

Strings

What does the following do?

"1-2-3-4-5-6".split("-")

• Return a list of numbers

  _{[1, 2, 3, 4, 5]}

• Return a list of strings

  _{["1", "2", "3", "4", "5"]}

• Return a string

  _"123456"

• Raise an Error

Answer explanation

Split is cutting into a list of the strings (even if it's numbers) based on a keyword passed as argument.

Note that we can apply method directly on strings (or lists, dictionaries) without going through a variable.

What is the purpose of the triple quotes """...""" ?

• It is exactly like double quotes

• You can put strings on several lines

• You can replace variables by their values

• It does not exist

Tags

Strings

What is the difference between single quotes strings '...' and double quotes strings "..."?

• Single quotes can only contain a single character

• Single quotes cannot have f-strings

• Single quotes allow to put string on several lines

• They are the same

Answer explanation

Single quotes and double quotes are the same, except for characters to escape: usually you use double quotes in general, and you use single quotes if you have many doubles quotes in the text

* "It's great"

* 'He said: "How are you?"'

Tags

Strings

What is the value of my_string in the following code?

_{my_string = "abcde"}

_{my_string[1] = "Z"}

• "abcde"

• "Zbcde"

• "aZcde"

• An Error has been raised

Tags

Strings