I have a list:
nums = [0, 1, 2, 3]
what I would like to do is loop though this list but then change the list. Basically when I loop through
nums = [0, 1, 2, 3] nums would need to change to:
nums = [current_element, 0, 1, 2] nums = [0, current_element, 1, 2] nums = [0, 1, current_element, 2] nums = [0, 1, 2, current_element]
Is there a way of changing
nums like this? I feel like there is a simple solution to this, but I’ve been stumped for hours.
You can pass a
map() object to the
for loop that generates the list you need at each iteration. For each index, we generate a new list using list slicing to replace the element at that index:
current_element = 42 nums = [0, 1, 2, 3] for lst in map(lambda x: nums[:x] + [current_element] + nums[x+1:], range(len(nums))): print(lst)
[42, 1, 2, 3] [0, 42, 2, 3] [0, 1, 42, 3] [0, 1, 2, 42]
This approach has two notable advantages:
- This doesn’t mutate the original list. If you need to access the original list for any reason, you can.
- You don’t need to worry about resetting values at the start/end of each iteration. If you need to implement this pattern several times, you don’t need to remember to replace the values each time.