Dictionary and Sets in Python

 Dictionary

d={

    "key1":"value1"

    "key2":"value2"

}

d[key1] # output = value1  # will show error if key is incorrect

Keys need to be of immutable data types eg, string,tuple or int

 every key is unique,d is unordered [so no indexing]**,mutable

Dictionary methods:

d.keys()==print value of all keys as list (class=dict_keys) (list)

output as dict_keys([list of keys])

d.values()==print all the values(list)

output as dict_values([list of values])

d.items()== create a list of multiple tuples each having 2 elements :1 key and 1 value.

output as dict_items([list of tuples])

d.update(d2)==add new item(s) of d2 in original dictionary at the end.

or d[new_key]=new_value

d.update("old_key","new_value")==replaces old value with new value

d.get("key",error_message/value)== shows the related value or none # no error[default error message=None]

print(d.get(...))

d.pop("key")

d.clear()

d.fromkeys(<a list of keys>,default_value_to_be_assigned)==create a new dict(if empty then default value ==None)

d2=d1.copy()   [deep copy]

s=d.popitem()==removes last key-value pair and assign it to s as tuple(maybe)

max,min, sum, in operator -works on key only

list1=sorted(d)

variable=d.setdefault("key","default_value")==when variable will be called it will return the value of key in dict if it exists else the default_value

for i in d: ==iterate for each key

while creating a dict. if their is repeated key then it will overwrite the previous value the the assigned value to the key will be the last entered value

len(d) and str(d) are valid functions

Merge two dictionaries

For Python 3.5+:

>>> dict_a = {'a': 1, 'b': 2}
>>> dict_b = {'b': 3, 'c': 4}
>>> dict_c = {**dict_a, **dict_b}
>>> dict_c
# {'a': 1, 'b': 3, 'c': 4}

SET 

s={1,2,3,4,1}

print(s)={1,2,3,4} #repetitive elements will be ignored

s.add(something) # can add tuple ,can't add list or dict (only add hashable contents)

unordered,unindexed,immutable

len()== give the number of elements

remove(8) : Updates the set S and removes 8 from S

pop() : Removes an arbitrary element from the set and returns the element removed.

clear() : Empties the set S

union({8, 11}) : Returns a new set with all items from both sets. #{1,8,2,3,11}

intersection({8, 11}) : Returns a set which contains only items in both sets. #{8}