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Extending a list in Python (5 different ways)
• Difficulty Level : Medium
• Last Updated : 11 Oct, 2019

Extending a list in python can be done is following ways:
1. Using append() function: We can append at the end of the list by using append() function. For appending any single value to the list or appending a list to the list, the syntax stays the same. But we can only append a single value at a time using append() function

 `# Python program to extend a list using append()`` ` `a ``=` `[``10``, ``12``, ``13``, ``17``] `` ` `# appending multiple values``a.append(``20``)``a.append(``22``)``print``(a)`

Output:

```[10, 12, 13, 17, 20, 22]
```

2. Using ‘+’ operator: We can add values by using the “+” operator. We can use [] to add any number of values to the list. Adding multiple values can be done by using ‘, ‘ values.

 `# Python program to extend a list using '+' `` ` `a ``=` `[``10``, ``12``, ``13``, ``17``] `` ` `# Appending single value``a ``=` `a ``+` `[``20``]`` ` `# append more then one values``a ``=` `a ``+` `[``30``, ``40``]``print``(a)`

Output:

```[10, 12, 13, 17, 20, 30, 40]
```

3. Using slicing: Using slicing in python, single or multiple values can be added to a list.

a[:0] = [x, y, z…]

Here a is the list in which the values(x, y, z..) are to be added. In this method the values are appended to the front of the list. `# Python program to extend a list using 'slicing' `` ` `# appending multiple value ``a ``=``[``10``, ``12``, ``13``, ``17``] `` ` `# add 1 number``a[:``0``] ``=` `[``30``]`` ` `# add two numbers``a[:``0``] ``=` `[``40``, ``50``]``print``(a)`

Output:

```[40, 50, 30, 10, 12, 13, 17]
```

4.Using chain(): Using chain() iterator function, we can extend a list by the syntax:

list(chain(a, [x, y, z..]))

Here a is the list in which the values(x, y, z..) are to be added. In this method the values are appended to the end of the list.

 `# python program to extend a list using ``# "chain" iterator functions``from` `itertools ``import` `*`` ` `a ``=` `[``10``, ``20``, ``30``]`` ` `# extend a list``print``(``list``(chain(a, [``40``, ``50``, ``60``])))`

Output:

```[10, 20, 30, 40, 50, 60]
```

5. Using Extend

 `# Python program to extend a list using extend() ``a ``=` `[``10``, ``12``, ``13``, ``17``] `` ` `b ``=` `[``30``, ``40``]`` ` `a.extend(b)`` ` `print``(a)`

Output:

```[10, 12, 13, 17, 30, 40]
```

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