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+--- Thread: myList.insert(index, element) question (/thread-34741.html)
myList.insert(index, element) question - ChrisF - Aug-27-2021
Why does the "insert.(index, element)" function work backwards in this for loop when used in the context "myList.insert(1, myList[v])"? Instead of adding 0, 1, and 2 to the list to the "myList[1]" location during iteration it will instead add 1 to myList[0], myList[1], and myList[2] during iteration.
Used outside of the loop "myList.insert(4, 8)" it will behave as expected adding 8 to "myList[4]" location.
myList = [1,2,3]
print("This is my initial list: ", myList)
for v in range(len(myList)):
print("This is v: ", v)
myList.insert(1, myList[v])
print("This is my list during iteration: ", myList)
print(myList)
myList.insert(4, 8)
print(myList)I couldn't upload an image of my output, but here is a copy/paste view of my output. Output:This is my initial list: [1, 2, 3]
This is v: 0
This is my list during iteration: [1, 1, 2, 3]
This is v: 1
This is my list during iteration: [1, 1, 1, 2, 3]
This is v: 2
This is my list during iteration: [1, 1, 1, 1, 2, 3]
[1, 1, 1, 1, 2, 3]
[1, 1, 1, 1, 8, 2, 3]RE: myList.insert(index, element) question - bowlofred - Aug-27-2021
What do you mean by "work backward"? The action is a bit confusing because you're modifying a list at the same time as you're reading it for information.
Start with [1, 2, 3].
First time through the loop, you tell it copy element 0 (which is a 1) to spot 1. -> [1, 1, 2, 3]
Next time through the loop, you tell it copy element 1 (which is now a 1) to spot 1 -> [1, 1, 1, 2, 3]
Next time through the loop, you tell it copy element 2 (which is now a 1) to spot 1 -> [1, 1, 1, 1, 2, 3]
It doesn't add 1, 2, 3 because myList has changed by the time the element is looked for.