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Is it possible in python to have a for-loop without index and item? I have something like the following:
list_1 = [] for i in range(5): list_1.append(3) The code above works fine, but is not nice according to the pep8 coding guidelines. It says: "Unused variable 'i'".
Is there a way to make a for-loop (no while-loop) without having neither the index nor the item? Or should I ignore the coding guidelines?
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Let us see how to check the index in for loop in Python. To check the index in for loop you can use enumerate() function. In Python, the enumerate() is an in-built function that allows us to loop over a list and count the number of elements during an iteration with for loop.
Using enumerate() is more beautiful but not faster for looping over a collection and indices.
Similar to any other programming language, the starting index of the for loop is 0 by default. However, the range of the iteration statement can be manipulated, and the starting index of the loop can be changed to 1 .
You can loop through the list items by using a while loop. Use the len() function to determine the length of the list, then start at 0 and loop your way through the list items by referring to their indexes. Remember to increase the index by 1 after each iteration.
You can replace i with _ to make it an 'invisible' variable.
See related: What is the purpose of the single underscore "_" variable in Python?.
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While @toine is completly right about using _, you could also refine this by means of a list comprehension:
list_1 = [3 for _ in range(5)] This avoids the ITM ("initialize, than modify") anti-pattern.
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