Why does this CSV to Python dictionary code give an IndexError?

Question

I'm writing code to make a global dictionary from a CSV-file in Python. The code doesn't do what I expect.

users.csv

name,money_in_pocket
siem,10
bart,10
ivar,10

test.py

import csv
global users
users = {}   
with open('users.csv', mode='r') as readuserfile:
    readusers = csv.reader(readuserfile, delimiter=',')
    next(readusers)
    for rows in readusers:
        users[rows[0]] = float(rows[1])

After running this piece of code, I expect the following to happen in the Shell:

>>>print(dict)
{'siem': 10, 'bart': 10, 'ivar': 10}

Instead, running test.py throws the next error:

Traceback (most recent call last):
----File "C:\\Users\\siemd\\Desktop\\test.py", line 8, in
--------users[rows[0]] = float(rows[1])
IndexError: list index out of range

If I understand this right, then the rows[0] and rows[1] cannot return a value, because they're out of the range of the 'list' (which is a read csv file).
But they should... Right?

Answer 1

You should check the length and type of rows . Tried your example:

$cat t.py
import csv
global users
users = {}
with open('users.csv', mode='r') as readuserfile:
    readusers = csv.reader(readuserfile, delimiter=',')
    next(readusers)
    for rows in readusers:
        users[rows[0]] = float(rows[1])

print users
$cat users.csv
name,money_in_pocket
siem,10
bart,10
ivar,10
$python t.py
{'ivar': 10.0, 'bart': 10.0, 'siem': 10.0}
$

Works fine. But if there is a newline at the end it fails:

$cat >> users.csv

$python t.py
Traceback (most recent call last):
  File "t.py", line 8, in <module>
    users[rows[0]] = float(rows[1])
IndexError: list index out of range
$

Adding a simple check helps:

$cat t.py
...
    for rows in readusers:
        if len(rows)==2:
          users[rows[0]] = float(rows[1])
...
$python t.py
{'ivar': 10.0, 'bart': 10.0, 'siem': 10.0}
$