# [Python](EN) Python List Comprehensions

Practice Python List Comprehensions

## Environment and Prerequisite

- Linux
- Python 3.X.X

## Python List Comprehensions

### List Comprehensions

```
results=[]
for i in range(10):
results.append(i*2)
```

```
results=[x*2 for x in range(10)]
```

`List Comprehensions`

: List comprehensions provide a concise way to create lists. It can make list much simpler.- It can be used when you make new list which is result of each element’s operation or subset elements of some conditions.

### Format

```
list_name = [element_format for clause]
```

- Cover with brackets(
`[ ]`

), add element format in the front and add for clause in the end. - As like below example, we can also use nested for loop.

### Examples

#### Square

```
results=[]
for i in range(10):
results.append(i**2)
```

```
results=[x**2 for x in range(10)]
```

#### Make tuple

```
results=[]
for x in [1,3,5]:
for y in [2,4,6]:
results.append((x,y))
```

```
results=[(x,y) for x in [1,3,5] for y in [2,4,6]]
```

#### Use with function

```
from math import pi
results=[]
for i in range(1, 6):
results.append(str(round(pi, i)))
```

```
from math import pi
results=[str(round(pi, i)) for i in range(1, 6)]
```

#### Nested loop

```
results=[]
for x in [1,2]:
for y in [3,4]:
for z in [5,6]:
results.append((x,y,z))
```

```
results=[(x,y,z) for x in [1,2] for y in [3,4] for z in [5,6]]
```

#### Use with if statement

```
results=[]
for x in range(20):
if x%2 == 0:
results.append(x)
```

```
results=[x for x in range(20) if x%2 == 0]
```