Why do I get this error (NoneType)?

Question

I know there are help forums on the NoneType error. But for the love of me I can’t save my coding.

counter=0
agesList=[]
for line in database:
    newlist=database[counter].split(',')
    counter=counter+1
    age=newlist[-2]
    agesList=agesList.append(age)
    #print(age)
print(agesList)

I have a document of comma separated values, and I split them all into their own list and take out the number I’m looking for which sits in the second to last positon of the newlist. If I print age I get all of the correct ages 1 by 1 throughout the loop. But if I try to append all of the age numbers onto my blank list I get this error:

agesList=agesList.append(age)
AttributeError: 'NoneType' object has no attribute 'append'

Can I please get some help on why I get this error? Thanks

Asked By: LittleAuditorium

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Source

Answer 1

You’re assigning a function call to your list which is why you’re overwriting your list.

Don’t do this:

agesList=agesList.append(age)

Simply do this:

agesList.append(age)

Answered By: eagle

Answer 2

Instead of agesList=agesList.append(age) use only agesList.append(age).

Because list.append() returns None and overrides your list.

Thus the first iteration of your for-loop will run fine, after that agesList is None and you will get the error you’re mentioning.

Answered By: Mike Scotty

Why do I get this error (NoneType)?

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