CODEWITHSUNDEEP
pythonpandasdataframespyderkeyerror
nielsen
nielsen

Reputation: 383

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

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)

Upvotes: 0

Views: 120

Answers (2)

Gabio
Gabio

Reputation: 9494

If B130317['LON'] is an empty list, B130317['LON'][i-1] for i=0 will throw KeyError: -1 exception. I don't know what is your business logic but maybe you should consider changing the loop to be:

for i in range(len(B130317['LON'])):
# your logic

Upvotes: 1

silver
silver

Reputation: 126

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)

Upvotes: 1

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