Dictionaries

chapter 5

Dictionary classic

D = {key1:value1, key2:value2, key3:value3}

Indexing

print(D['key'])

print keys

print(D.keys())

print values

print(D.values())

print whole list

print(D.items())

Membership test for key

'keys' in D

Change item

D['b']= 'changed item'

Length of dictionary items

print(len(D))

Merge F with D, using D's keys to update F's keys

F.update(D)

Remove key 'a' and return its associated value

print(D.pop('a'))

add key (e) and a value to D

D['e']= value

change what key (e) equals

D['e'] = 'new value'

list of the keys of D

list(D.keys())

list of the values of D

L_values = list(D.values())

• If key exists → return its value

• If key doesn't exist → return default

value = D.get('d',default value)

Comprehension Purpose

replace short for loop

dictionary comprehension classic

{key: value for key in iterable}

{key: value for (key, value) in iterable}

set comprehension classic

{f(x) for x in iterable}