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mkdocs/docs/Programmation/Python/set.md
2019-03-15 20:20:37 +01:00

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# Set
Une liste est une collection **non ordonnée** et **non indexée**. On ne peut pas modifier un item, mais on peut en ajouter.
##### Créer un set:
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set
{'alpha', 'beta', 'gamma'}
```
```python
# Constructor set()
>>> un_set = set(("alpha", "beta", "gamma"))
>>> un_set
{'gamma', 'alpha', 'beta'}
```
##### Ajouter un item:
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set.add("delta")
>>> un_set
{'gamma', 'alpha', 'beta', 'delta'}
```
##### Ajouter plusieurs items:
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set.update(["delta","zeta","epsilon"])
>>> un_set
{'zeta', 'alpha', 'beta', 'delta', 'gamma', 'epsilon'}
```
##### Longueur d'un set:
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> print(len(un_set))
3
```
##### Supprimer un item (remove):
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set.remove("beta")
>>> un_set
{'gamma', 'alpha'}
```
##### Supprimer un item (discard):
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set.discard("beta")
>>> un_set
{'gamma', 'alpha'}
```
##### Vider un set:
```python
>>> un_set = {"alpha", "beta", "gamma"}
>>> un_set.clear()
>>> un_set
set()
```
##### Supprimer un set:
```python
>>> del un_set
>>> un_set
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'un_set' is not defined
```
##### Boucle:
```python
un_set = {"alpha", "beta", "gamma"}
for x in un_set:
print(x)
alpha
beta
gamma
```
##### Test si un item est présent dans le set:
```python
un_set = {"alpha", "beta", "gamma"}
print("alpha" in un_set)
True
```
#### Méthodes:
| Méthodes | Description |
| ----------------------------- | ----------- |
| add() | |
| clear() | |
| copy() | |
| difference() | |
| difference_update() | |
| discard() | |
| intersection() | |
| intersection_update() | |
| isdisjoint() | |
| issubset() | |
| issuperset() | |
| pop() | |
| remove() | |
| symmetric_difference() | |
| symmetric_difference_update() | |
| union() | |
| update() | |