# Python Tuples: A Complete Guide

Tuples are an important data structure in Python which are quite similar to [Python lists](https://fjolt.com/article/python-lists). The main difference between tuples and lists, is tuples **cannot** be modified. Once it's created, it is fixed and unchangeable. Tuples are faster than lists, so if you know your data won't change, it's the correct way to go. Tuples are often used for iterating through a list of fixed items we know won't change.

In this guide, we'll cover how to use Tuples, as well as some of the methods and things you'd want to do with them. To start, let's define a new Tuple:
```python
myTuple = ("my", "new", "tuple")
print(myTuple) # ('my', 'new', 'tuple')
``` 

You may also see tuples being defined without brackets. A list of comma separated values also automatically becomes a tuple:
```python

myTuple = "my", "new", "tuple"
print(myTuple) # ('my', 'new', 'tuple')
```

Trying to change a tuple, will result in an error:
```python
myTuple = ("my", "new", "tuple")
myTuple[0] = "your" # TypeError: 'tuple' object does not support item assignment
```

As you might expect, though, that means we can access tuple data using the syntax `myTuple[0]`, to refer to the item at index 0.

Tuples may contain duplicates, so they aren't limited by uniqueness like [Python sets](https://fjolt.com/article/python-sets):
```python
myTuple = ("my", "new", "tuple", "tuple")
print(myTuple) #  ('my', 'new', 'tuple', 'tuple' )
```

Finally, tuples can also be nested, just like lists:
```python
myTuple = ( ("nested", "tuple"), "my", "new", "tuple", "tuple")
```

## Checking Membership using Tuples
As with [Python sets](https://fjolt.com/article/python-sets), we can test for membership using tuples using the `in` and `not in` keywords. For example, below, we check if `apple` is in our tuple of `fruits`:
```python
fruits = ("apple", "pear", "strawberry")

print("apple" in fruits) # True
print("apple" not in fruits) # False
```

## Combining Tuples
Since we can't modify tuples, if we want to make an updated version of a tuple we need to combine it. That can be done by adding them together:
```python
tupleOne = ("one", "two")
tupleTwo = ("three", "four")
tupleThree = tupleOne + tupleTwo
print(tupleThree) # ("one", "two", "three", "four")
```

## Sorting a Tuple

Since tuples are ordered like [Python lists](https://fjolt.com/article/python-lists), we can also sort our tuples. However, a tuple has no method `sort()`, so we have to use the `sorted()` function. Why can't we use a `sort()` method? Since tuples are immutable! So we have to define a new tuple using `sorted()`:
```python
myTuple =  ("a", "c", "e", "b", "f", "d", "g", "z", "w", "x")
myNumberTuple = (1, 3, 5, 2, 7, 4, 6)

newTuple = sorted(myTuple)
newNumberTuple = sorted(myNumberTuple)

print(newTuple) # ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'w', 'x', 'z')
print(newNumberTuple) # (1, 2, 3, 4, 5, 6, 7)
```

As with `list.sort()`, if you try to sort with multiple types - like integers and strings, you'll end up getting an error. Here we have to use the additional arguments of `sorted()` to sort our list:
- `key` gives us a number which will be used to compare the list content
- `reverse` if set to true will reverse the order.

For example, to put all values which are `b` at the start of a tuple, we could try something like this:
```python
def isB(letter):
    if(letter == "b"):
        return 1
    else:
        return 0

myTuple = ("b", "c", "b", 5, "f", "b", 2, "z", "a", "x")

newTuple = sorted(myTuple, key=isB, reverse=True)

print(newTuple) # ['b', 'b', 'b', 'c', 5, 'f', 2, 'z', 'a', 'x']
```

Here we define a function `isB` which is used in `sorted()` to pass each item in the tuple to the function. If the item in the tuple is `b`, then the order for that item is set to `1`, otherwise it's `0`. This let's us order our list based on conditions other than alphanumeric order.

## Conclusion
Thanks for reading. You can learn more about Python data collections below:

- [Python Data Collections](https://fjolt.com/python-data-collections)
- [Python Data Collections: Lists](https://fjolt.com/article/python-lists)
- **Python Data Collections: Tuples**
- [Python Data Collections: Sets](https://fjolt.com/article/python-sets)
- [Python Data Collections: Dictionaries](https://fjolt.com/article/python-dictionaries)