# merge two lists using unpacking method in Python

There are multiple ways to merge two lists in Python. In my earlier article, we have seen merging two lists using the plus (+) operator and the list.extend() methods. In this article, let’s see how to concatenate two lists using the unpacking method and the sum() method.

## Using unpacking method with star (*) expression

One of the common way to concatenate or merge multiple lists is by using star (*) expression. Below is an example.

```# Merging two lists using unpacking method
list_A = [100, 200, 300, 400]
list_B = [400, 1000, 2000]
list_Result = [*list_A, *list_B]
print(list_Result)
```

Result:

```[100, 200, 300, 400, 400, 1000, 2000]
```

The advantage of using this unpacking method is, you can even merge lists with range and tuple. Here is an example of concatenating a list with a range.

```# Merging a list and a range using unpacking method
list_A = [100, 200, 300, 400]
range_A = range(400, 1000, 100)
list_Result = [*list_A, *range_A]
print(list_Result)
```

Result:

```[100, 200, 300, 400, 400, 500, 600, 700, 800, 900]
```

If you try to merge a list and a range using the plus (+) operator, you will get the error “TypeError: can only concatenate list (not “range”) to list“. In such situations, this unpacking method of merging will be helpful.

## Using sum() function

Using the sum() function is a variation of the plus (+) operator to merge two lists. Here is an example.

```# Merging two lists using sum
list_A = [100, 200, 300, 400]
list_B = [400, 1000, 2000]
list_Result = sum([list_A, list_B], [])
print(list_Result)
```

Result:

```[100, 200, 300, 400, 400, 1000, 2000]
```

## Merge two lists using addition assignment (+=)

Below is another way to use the plus (+) operator (actually addition assignment += ) to concatenate lists.

```list_A = [100, 200, 300, 400]
list_B = [400, 1000, 2000]
list_A += list_B
print(list_A)
```

Result:

```[100, 200, 300, 400, 400, 1000, 2000]
```

Hope this is helpful. In the next article we will see how to merge two or more dictionaries in Python.

## Reference

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