Submitted by BoomBox

over 11 years

18/18 AttributeError: 'NoneType' object has no attribute 'append'

n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]


def flatten(lists):
    results = []
    for i in range(0,len(lists)):
        results = results.append(lists[i])
    return results

print flatten(n)

Traceback (most recent call last): File “python”, line 10, in

Anyone know what is wrong?

Answer 531f073352f863ed72002f0f

3 votes

Permalink

I got this to work:

n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]
# Add your function here
def flatten(lists):
    results = []
    for numbers in lists:
        for x in numbers:
            results.append(x)
    return results

print flatten(n)

Submitted by systemSurfer29094

over 11 years

1 comments

Submitted by digitalSlayer22298

over 11 years

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Answer 531f639280ff33cd91004dce

1 vote

Permalink

n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]


def flatten(lists):
    results = []
    for i in range(0,len(lists)):
        results = results.append(lists[i])
    return results

print flatten(n)

This way you are basically trying to append lists inside results.

Variable n is a list of lists! Which means when you iterate through n it will simply return more lists! To get elements you need to iterate inside the list which is already located inside an list.

Submitted by linaran

over 11 years

1 comments

Submitted by Choki_Wukong

over 11 years

For some reason, I can’t get the range method to work for this lesson. I feel like I did the same thing as above but I used “x” instead of “i” for the variable name in the for loop.

Answer 531fc23e548c35d81a004bce

0 votes

Permalink

Really?

Submitted by cybershats

over 11 years

Answer 531fdaa6548c35cbc10073cc

0 votes

Permalink

Ah i see, so it’s like n[1] = [ 1, 2, 3] n[2] = [ 4, 5, 6, 7, 8, 9]

Okay, I think I get it now.

Submitted by BoomBox

over 11 years

2 comments

Submitted by linaran

over 11 years

It’s exactly like that! => if you want to know how is it possible check out pointers in C,

Submitted by easternlai

over 11 years

me too :(

Answer 55ed3d5786f55274b700056e

0 votes

Permalink

This is the Correct answer.

n = [[1, 2, 3], [4, 5, 6, 7, 8, 9]]

def flatten(lists):
 results = [ ]
 for numbers in lists:
    print numbers
    for i in numbers:
        print i
        results.append(i)
 return results
print flatten(n)