Error- local variable referenced before assignment

Question

What I'm sure is another simple error, but I'm going around in circles. I'm trying to get it to show the first 10 lines in a csv using a function. I can get 1 line to show before it throws an error. Maybe my rows=0 needs to be moved down further, but I'm not sure and my attempts at moving it hasn't worked?


rows = 0

def lines():
    with open('iamacsvfile.csv') as file:
        dictreader = csv.DictReader(file)
        for row in dictreader:
            print(row)
            rows=rows+1
            if(rows>=10):
                break

lines()

UnboundLocalError                         Traceback (most recent call last)
Input In [57], in <cell line: 14>()
     11             if(rows>=5):
     12                 break
---> 14 lines()

Input In [57], in lines()
      8 for row in dictreader:
      9     print(row)
---> 10     rows=rows+1
     11     if(rows>=5):
     12         break

UnboundLocalError: local variable 'rows' referenced before assignment

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It depends if you want *rows* to be local or global. If the former then move *rows = 0* inside the function. If the latter add *global rows* inside the function — DarkKnight, Sep 08 '22 at 10:11

score 0 · Accepted Answer · answered Sep 08 '22 at 10:10

0

This should work:

def lines():
    rows = 0
    with open('iamacsvfile.csv') as file:
        dictreader = csv.DictReader(file)
        for row in dictreader:
            print(row)
            rows=rows+1
            if(rows>=10):
                break

lines()

answered Sep 08 '22 at 10:10

Roy

398
2
12

Thanks. I was trying further down. I'll get there... hopefully – dreamkeeper Sep 08 '22 at 10:22

score 0 · Answer 2 · answered Sep 08 '22 at 10:11

Your rows is outside the function so the lines function cannot access the variable. Try moving rows inside the lines function like this.

def lines():
    rows = 0

    with open('iamacsvfile.csv') as file:
        dictreader = csv.DictReader(file)
        for row in dictreader:
            print(row)
            rows=rows+1
            if(rows>=10):
                break

lines()

score 0 · Answer 3 · answered Sep 08 '22 at 10:12

0

You haven't defined rows.

But you don't need that, since csv.DictReader has line_num property, which increases with each iteration. It's better to use:

for row in dictreader:
    print(row)
    if dictreader.line_num >= 10:
        break

answered Sep 08 '22 at 10:12

xaleel

173
5

1

That's good to know. Still learning and so many ways to do something. I'm taking the long winded route currently. – dreamkeeper Sep 08 '22 at 10:23

Error- local variable referenced before assignment

3 Answers3