103 lines
1.7 KiB
Markdown
103 lines
1.7 KiB
Markdown
---
|
|
tags: [python, data-structures]
|
|
---
|
|
|
|
Tuples are one of the main data-structures or containers in Python. Tuples are
|
|
useful in cases where you want to group related data and ensure that it will not
|
|
change.
|
|
|
|
Tuples have the following properties:
|
|
|
|
- They are **ordered**
|
|
- They have a **fixed size**
|
|
- They are **immutable** and cannot be modified
|
|
- **Allow duplicate** members
|
|
- They are **indexed**
|
|
|
|
> In essence a tuple is a list that is immutable.
|
|
|
|
As with all containers in Python they permit any data type.
|
|
|
|
> Tuples are denoted with `(...)`
|
|
|
|
## Basic usage
|
|
|
|
```python
|
|
tup1 = (1, 3, 5, 7)
|
|
print(tup1[2])
|
|
|
|
# 5
|
|
```
|
|
|
|
> Really you should know in advance how long your tuple is going to be but if
|
|
> you just do `tup = ('shoe')` this will be processed by Python as a single
|
|
> string. Instead if you want to indicate that the tuple may be expanded later
|
|
> use `tup = ('shoe',)`. The comma converts it from a string to a tuple.
|
|
|
|
## Slicing
|
|
|
|
```python
|
|
tup1 = (1, 3, 5, 7)
|
|
|
|
print(tup1[1:3])
|
|
print(tup1[:3])
|
|
print(tup1[1:])
|
|
print(tup1[::-1])
|
|
|
|
"""
|
|
(3, 5)
|
|
(1, 3, 5)
|
|
(3, 5, 7)
|
|
(7, 5, 3, 1)
|
|
"""
|
|
```
|
|
|
|
## Looping
|
|
|
|
```python
|
|
tup3 = ('apple', 'pear', 'orange', 'plum', 'apple')
|
|
for x in tup3:
|
|
print(x)
|
|
|
|
"""
|
|
apple
|
|
pear
|
|
orange
|
|
plum
|
|
apple
|
|
"""
|
|
```
|
|
|
|
## Useful methods and predicates
|
|
|
|
```python
|
|
tup3 = ('apple', 'pear', 'orange', 'plum', 'apple')
|
|
|
|
# Count instances of a member
|
|
print(tup3.count('apple'))
|
|
# 2
|
|
|
|
# Get index of a member
|
|
print(tup3.index('pear'))
|
|
# 1
|
|
|
|
# Check for membership
|
|
if 'orange' in tup3:
|
|
print('orange is in the Tuple')
|
|
|
|
# orange is in the Tuple
|
|
```
|
|
|
|
## Nest tuples
|
|
|
|
```python
|
|
|
|
tuple2 = ('John', 'Denise', 'Phoebe', 'Adam')
|
|
tuple3 = (42, tuple1, tuple2, 5.5)
|
|
print(tuple3)
|
|
|
|
# (42, (1, 3, 5, 7), ('John', 'Denise', 'Phoebe', 'Adam'), 5.5)
|
|
|
|
```
|
|
|
|
// TODO: How to flatten a tuple?
|