# Python Lists

Lists are used to store multiple items in a single variable. A list is a collection which is ordered and changeable. Allows duplicate members.

## Creating a List

Lists are created using square brackets:

```python
thislist = ["apple", "banana", "cherry"]
print(thislist)
```

## Access Items

List items are indexed, the first item has index `[0]`, the second item has index `[1]` etc.

```python
thislist = ["apple", "banana", "cherry"]
print(thislist[1]) # Output: banana
```

## Change Item Value

To change the value of a specific item, refer to the index number:

```python
thislist = ["apple", "banana", "cherry"]
thislist[1] = "blackcurrant"
print(thislist)
```

## List Comprehension

List comprehension offers a shorter syntax when you want to create a new list based on the values of an existing list.

```python
fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = [x for x in fruits if "a" in x]
print(newlist)
```

See [[programming/python/list-comprehensions]] for more details.

## List Methods

Python has a set of built-in methods that you can use on lists.

*   `append()`: Adds an element at the end of the list
*   `clear()`: Removes all the elements from the list
*   `copy()`: Returns a copy of the list
*   `count()`: Returns the number of elements with the specified value
*   `extend()`: Add the elements of a list (or any iterable), to the end of the current list
*   `index()`: Returns the index of the first element with the specified value
*   `insert()`: Adds an element at the specified position
*   `pop()`: Removes the element at the specified position
*   `remove()`: Removes the item with the specified value
*   `reverse()`: Reverses the order of the list
*   `sort()`: Sorts the list

## Loop Through a List

You can loop through the list items by using a `for` loop:

```python
thislist = ["apple", "banana", "cherry"]
for x in thislist:
  print(x)
```

[[programming/python/python]]