How to understand what is wrong with my Python loop code

Question

I have written this code to extract only digits from a text file and then calculate sum of those values extracted . But I am getting 0 as answer which should 285701 in actual. I don't understand what I am doing wrong even after working on it for long, I am not very experienced in programming just started learning.

import re
fname = open("http://py4e-data.dr-chuck.net/regex_sum_1501185.txt")
sum = 0
value = list()
for line in fname:
     line = re.findall("[0-9]+", line)
     value = value + line
for x in value:
     sum = sum + int(x)
print(sum)

I have some good and some bad news: the good news: it's working for me, the bad news: it's working for me. — Mike Scotty, Jul 17 '22 at 21:22
This code works for me. Are you sure the `open()` call is correct? `open()` only works for local filenames, not on web urls. — John Gordon, Jul 17 '22 at 21:22
You can't open web urls with `open()` look here: https://stackoverflow.com/questions/1393324/given-a-url-to-a-text-file-what-is-the-simplest-way-to-read-the-contents-of-the — noah1400, Jul 17 '22 at 21:28

noah1400 · Accepted Answer · 2022-08-08T12:45:39.443

You can't open web urls with open() you need to use urllib.request.urlopen():

import urllib.request
import re
fname = urllib.request.urlopen("http://py4e-data.dr-chuck.net/regex_sum_1501185.txt")
data = fname.read().decode()
data = data.split('\n')
sum = 0
value = list()
for line in data:
     nums = re.findall("[0-9]+", line)
     value = value + nums
for x in value:
     sum = sum + int(x)
print(sum)

Output:

You need to be careful with your variable names naming your variable sum causes that you won't be able to use the builtin function sum()

It would be better if your code looks like that:

import urllib.request
import re
fname = urllib.request.urlopen("http://py4e-data.dr-chuck.net/regex_sum_1501185.txt")
data = fname.read(50000).decode()
data = data.split('\n')
value = list()
for line in data:
     line = re.findall("[0-9]+", line)
     value = value + [int(i) for i in line]
print(sum(value))

Docs

How to understand what is wrong with my Python loop code

1 Answers1