Module 0.5.0 - Dictionaries, Tuples, Sets

• more data structures

0.5.1 - Dictionaries

• an array type that can list multiple keys [items] and assign each key a value [definition]

• dictionaries have no order

Initialization

• created using curly braces "{}"

• keys in between the curly braces are seperated by a comma ","

• each key is assigned a value by using a colon ":"

my_dict = {"name":"cosmo", "age":100, "occupation":"hacker"}

dictionaries can be indexed

print(my_dict["name"])
>>> "cosmo"

values can be added or changed through the assignmetn operator

nums = {"one":1, "two":2, "three":5}
nums["four"] = 4
nums["three"] = 3
print(nums)
>>> {"one":1, "two":2, "three":3, "four":4}

"in" and "not" boolean operators in work with dictionary keys

print("two" in nums)
>>> True

print("one" not in nums)
>>> False

"get" method, returns the key's value, can return specified value if key is not found

• if no return value is specified, it will return "None"

print(nums.get("three"))
>>> 3

print(nums.get("five", "key does not exist"))
>>> "key does not exist"

0.5.2 - Tuples

• lists that can not be edited, immutable

• iterate faster than lists

• created using parenthesis "()" or just seperating values with commas ","

  • values are seperated by commas "."

my_tuple = (1, 2, 3, 4, 5)
my_other_tuple = 1, 2, 3, 4, 5

tuples can be indexed

print(my_tuple[3])
>>> 4

list slicing can also be done with tuples

print(my_tuple[1:3])
>>> (2, 3, 4)

0.5.3 - Sets

• assign multiple values to one variable

• sets are not ordered, they can not be indexed

• they can not contain duplicate items

• can use most of the list methods

• created using curly braces "{}" or the "set" function, takes list as argument

• each item is seperated by a comma ","

set_using_braces = {1, 2, 3, 4, 5}
set_using_function = set([1, 2, 3, 4, 5])

sets can use "in" and "not" boolean operators

my_set = {"apple", "orange", "bannana"}
print("apple" in my_set)
>>> True

"add" method, add item to end of set

• this replaces "append" method

my_set.add("pear")
print(my_set)
>>> {"apple", "orange", "bannana", "pear"}

0.5.4 - Set Operators

sets have unuiqe operators for comining with other sets

set1 = {0, 2, 4, 6, 8, 9}
set2 = {2, 3, 5, 7, 9, 6}

"union" operator, combines two sets into one [with no duplicate items]

• created using the pipe "|"

print(set1 | set2)
>>> {0, 2, 3, 4, 5, 6, 7, 8, 9}

"intersection" operator, combines two sets into one [with items only in both sets]

• created using the ampersand "&"

print(set1 & set2)
>>> {9, 2, 6}

"difference" operator, combines two sets into one [with items in the first, but not in the second]

• created using the minus "-"

print(set1 - set2)
>>> {0, 8, 4}

"symmetric difference" operator, combines two sets into one [with items in either set]

• created using carrot "^"

print(set1 ^ set2)
>>> {0, 3, 4, 5, 7, 8}

0.5.5 - Iterable Unpacking

assign each item in an iterable [lists, dictionaries, tuples, sets] to a variable

nums = (1, 2, 3)
one, two, three = nums

print(two)

>>> 2

allows for easy value swapping for variables

one, two = two, one

if there is an asterisk * placed before the variable, it will assign itself to the remaining values

lowest_num, *other_nums, highest_num = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

print(other_nums)
>>> [2, 3, 4, 5, 6, 7, 8, 9]