# Reverse Array In Python

An array is a collection of items stored together in sequential memory locations. The idea is to store multiple items of the same type together.


![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1650717712473/7E-376C6M.png)


So there are three ways we can reverse an array in python,

## 1. Slicing

We can use slicing to turn any normal list array into a reverse list array. 

```
list = [1,2,3,4]
print(list[::-1])
```
```
Result: 4,3,2,1
```

### How does slicing work? 
Slicing has three values `start` `stop` and `step` which makes it easier for us to reverse the list here. Some of the examples for slicing would be:

```
list[start:stop]  # items start through stop -1
list[start:]      # items start through the rest of the array
list[:stop]       # items from the beginning through stop -1
list[:]           # a copy of the whole array
list[start:stop:step] # start through not past stop, by step
```

To make it easier we can look at this diagram below where positive values mean sequential increment and negative values mean the complete opposite.

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1650719122293/kiMgCrv4x.png)


As you can see we only used `step` here `list[::-1]` in our code to reverse the array and that is because this `step` works with items from first to last and the amount you put are the steps it will take, for example, if we put this `list[::2]` it will print only 1 and 3 because the step started from 1 and then skipped 1 and 2 and found 3 so it shows 1 and 3!

Now if you put this `list[::1]` it will show the all 1,2,3,4 because it is taking 1 and then taking one step and finding 2 then again another step finding 3 this way it will continue. 


So now if we `list[::-1]` put this it goes to the last items and starts from there so the whole list gets reversed!





## 2. Reverse()

Python has a built-in method reverse() that automatically reverses the order of the list arrays right at the original place.

```
list = [1,2,3,4] 
print(list)
list.reverse()
```
```
Result: 4,3,2,1
```
## 3. Reversed()
Another similar method is there which is `reversed()` when passed with a list returns an iterable in reverse order. 

```
arr_list = [1,2,3,4] 
print(list(reversed(arr_list)))
```
```
Result: 4,3,2,1
```