How to train your python: iterables (FR)

Jordi Riera
● Software developer @ Rodeo FX
● Founder @ cgstudiomap.org
● 8 ans à écrire du python
● kender.jr@gmail.com
● @jordiriera_cg
● https://www.linkedin.com/in/jordirieracg/
● https://github.com/foutoucour/

How To Train Your Python
Les bases sur les iterables

Iterables
+ de 10 types d’iterables

liste, et pas que
● List & deque
● Tuple & namedtuple
● String
● Set & frozenset
● Dict, Ordereddict, ChainMap, Counter & defaultdict
● Generators
● Range, zip, map, file object, et autres.

Lequel choisir?
● List, deque, tuple, string, generators, Ordereddict: ordonnés
● Tuple, frozenset: immuables (well... kind of... :( )
● Set & frozenset: caractère unique
● Dict, Ordereddict, ChainMap, Counter & defaultdict: mapping
● String: ... ben... string quoi...
● Generators, range, zip, map, etc: optimisation, consommation

for loop
languages = [‘php’, ‘ruby’, ‘python’]
frameworks = [‘symfony’, ‘ruby on rails’, ‘django’]
for i in range(len(languages)):
print(languages[i] + ‘: ’ + frameworks[i])

for loop
languages = [‘php’, ‘ruby’, ‘python’]
frameworks = [‘symfony’, ‘ruby on rails’, ‘django’]
for i, language in enumerate(languages):
print(‘: ’.join([language, frameworks[i]]))
for language, framework in zip(languages, frameworks):
print(‘: ’.join([language, framework]))

Set
random_numbers = [ 3, 4, 4, 1, 2, 3, 1]
set(random_numbers)
>>> {1, 2, 3, 4}
frozenset(random_numbers)
>>> frozenset({1, 2, 3, 4})

Set
Sets acceptent les
opérations mathématiques:
● Union
● Intersection
● Difference
● Et d’autres opérations
plus chelou, mais ça fait
de jolies figures

mapping = dict() # ou {}
if not language in languages:
mapping[language] = []
mapping[language].append(framework)
dict

mapping = defaultdict(list)
mapping[language].append(framework)
mapping = {}
for l, framework in zip(languages, frameworks):
mapping.setdefault(l, []).append(framework)
dict

dict
mapping = {‘php’:[‘symfony’], ‘ruby’:[’ruby on rails’],
‘python’:[’django’]}
for language in mapping:
print(language)
for language, frameworks in mapping.items():
print(language, frameworks)

dict
mapping = {‘php’:[‘symfony’], ‘ruby’:[’ruby on rails’],
‘python’:[’django’]}
print(mapping[‘python’])
del mapping[‘python’]
print(mapping.get(‘python’, ‘flask’))
Mapping[‘python’] = ‘pyramid’

muabilité
# Les listes sont muables. Elles peuvent être mis à jour:
list1 = [1,]
list1.append(2)
list1 == [1, 2]
Et d’autres méthodes...
list2 = [1,]
list2.insert(0, 2)
list2 == [2, 1]

muabilité
# Cool mais...
list2 = list1
list1.append(3)
list2 == [1, 2, 3]
# list2 “pointe” vers list1.
# list1 et list2 sont la même
liste en fait...

muabilité
# Solution
list2 = list1[:]
# list2 est une liste avec
tous les éléments de list1
# you’re welcome ;)

# Les tuples sont immuables,
# ils ne peuvent pas être mis à jour:
tuple1 = (1,)
tuple1.append(2)
Raise AttributeError
immuabilité

# enfin...
list1 = [1,]
tuple1 = (1, list1)
list1.append(2)
tuple1 == (1, [1, 2])
# pas cool bro!
immuabilité

Compréhension à la portée de tous!
list1 = [x for x in z if not x == ‘foo’]
gen = (x for x in z if not x == ‘foo’)
# Nope c’est pas un tuple! Mais un générateur.
set1 = {x for x in z if not x == ‘foo’}
dic1 = {x: x.bar for x in z if not x == ‘foo’}

Questions?
● kender.jr@gmail.com
● @jordiriera_cg
● https://www.linkedin.com/in/jordirieracg/
● https://github.com/foutoucour/

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