[FIXED] Why does this ID generating code make a KeyError: -1

Issue

A problem in this part of my code causes KeyError: -1

Do any of you know what might cause this?

for i in range(len(B130317)):
    if B130317['LON'][i] != B130317['LON'][i-1]:
        currentID += 1
    newID.append(currentID)

Solution

based on the comments of @Badgy:

for i in range(1,len(B130317)):
    if B130317['LON'][i] != B130317['LON'][i-1]:
        currentID += 1
    newID.append(currentID)

or:

for i in range(len(B130317)-1):
    if B130317['LON'][i] != B130317['LON'][i+1]:
        currentID += 1
    newID.append(currentID)

Answered By - silver