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Python – Double each List element
• Last Updated : 01 Mar, 2020

Sometimes, while working with data, we have just a simple application in which we require to double the contents of a list and make it 100% increase in its magnitude. This is having application in web development and machine learning domains. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop
This the brute force way in which this task can be performed. In this, we just add the same element again to that index element and all the contents of list are added to itself i.e doubled.

 `# Python3 code to demonstrate ``# Double List``# using loop`` ` `# Initializing list``test_list ``=` `[``12``, ``67``, ``98``, ``34``, ``43``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# Double List``# using loop``res ``=` `[]``for` `ele ``in` `test_list:``    ``res.append(ele ``+` `ele)``     ` `# printing result ``print` `(``"Double List is : "` `+` `str``(res))`
Output :
```The original list is : [12, 67, 98, 34, 43]
Double List is : [24, 134, 196, 68, 86]
```

Method #2 : Using list comprehension
This task can also be performed using list comprehension. This is similar to above function. Just the difference is that its compact and one liner.

 `# Python3 code to demonstrate ``# Double List``# using list comprehension`` ` `# Initializing list``test_list ``=` `[``12``, ``67``, ``98``, ``34``, ``43``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# Double List``# using list comprehension``res ``=` `[ele ``+` `ele ``for` `ele ``in` `test_list]``     ` `# printing result ``print` `(``"Double List is : "` `+` `str``(res))`
Output :
```The original list is : [12, 67, 98, 34, 43]
Double List is : [24, 134, 196, 68, 86]
```

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