# Python List Comprehensions

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

## Syntax

```python
newlist = [expression for item in iterable if condition == True]
```

The return value is a new list, leaving the old list unchanged.

## Examples

### Basic Iteration

Instead of using a `for` loop:

```python
fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = []

for x in fruits:
  if "a" in x:
    newlist.append(x)

print(newlist)
```

You can do this in one line:

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

print(newlist)
```

### Condition

The condition is like a filter that only accepts the items that valuate to `True`.

```python
newlist = [x for x in fruits if x != "apple"]
```

### Expression

The expression is the current item in the iteration, but it is also the outcome, which you can manipulate before it ends up like a list item in the new list:

```python
newlist = [x.upper() for x in fruits]
```

[[programming/python/python]]