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Python – Remove Units from Value List
• Last Updated : 03 Jul, 2020

Sometimes, while working with Python value lists, we can have a problem in which we need to perform removal of units that come along with values. This problem can have direct application in day-day programming and data preprocessing. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [“54 cm”, “23 cm”, “12cm”, “19 cm”], unit = “cm”
Output : [’54’, ’23’, ’12’, ’19’]

Input : test_list = [“54 cm”], unit = “cm”
Output : [’54’]

Method #1 : Using `regex()` + list comprehension
The combination of these functions can be used to solve this problem. In this, we approach by extracting just the numbers using regex, and remove rest of string units.

 `# Python3 code to demonstrate working of ``# Remove Units from Value List``# Using list comprehesion + regex()``import` `re`` ` `# initializing list``test_list ``=` `[``"54 kg"``, ``"23 kg"``, ``"12kg"``, ``"19  kg"``] `` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing unit ``unit ``=` `"kg"`` ` `# Remove Units from Value List``# Using list comprehesion + regex()``res ``=` `re.findall(``'\d+'``, ``' '``.join(test_list))`` ` `# printing result ``print``(``"List after unit removal : "` `+` `str``(res))`
Output :

```The original list is : ['54 kg', '23 kg', '12kg', '19  kg']
List after unit removal : ['54', '23', '12', '19']
```

Method #2 : Using `replace() + strip()` + list comprehension
The combination of above functions can be used to solve this problem. In this, we perform the task of replacing unit with empty string to remove it using replace() and stray spaces are handled using strip().

 `# Python3 code to demonstrate working of ``# Remove Units from Value List``# Using replace() + strip() + list comprehension``import` `re`` ` `# initializing list``test_list ``=` `[``"54 kg"``, ``"23 kg"``, ``"12kg"``, ``"19  kg"``] `` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing unit ``unit ``=` `"kg"`` ` `# Remove Units from Value List``# Using replace() + strip() + list comprehension``res ``=` `[sub.replace(unit, "").strip() ``for` `sub ``in` `test_list]`` ` `# printing result ``print``(``"List after unit removal : "` `+` `str``(res))`
Output :
```The original list is : ['54 kg', '23 kg', '12kg', '19  kg']
List after unit removal : ['54', '23', '12', '19']
```

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