Why is all the data getting appended to the list

Question

paid_students=[]
for students in enrollments:
    if students['days_to_cancel']==None or students['days_to_cancel']>7:
        paid_students.append(students)
print len(paid_students)

Output:

The value of len(enrollments) is also 1640. Why are all the rows getting appended to the paid_students list even though many rows in the enrollments have ['days_to_cancel'] values having wide ranges.

Example data for enrollments

{u'account_key': u'448',
 u'cancel_date': u'2014-11-10',
 u'days_to_cancel': u'5',
 u'is_canceled': u'True',
 u'is_udacity': u'True',
 u'join_date': u'2014-11-05',
 u'status': u'canceled'}

{u'account_key': u'448',
 u'cancel_date': u'2015-01-27',
 u'days_to_cancel': u'0',
 u'is_canceled': u'True',
 u'is_udacity': u'True',
 u'join_date': u'2015-01-27',
 u'status': u'canceled'}

Source-Udacity

@AshKetchum yes it was asked in the question that the 'days_to_cancel' have to be greater than 7. — Mehul Bhatia, May 30 '17 at 06:40
You are comparing *strings* to an integer. `u'' > 7` is always true in Python 2, because numbers are always ordered before other object types. Convert to the value to an integer *first*. — Martijn Pieters, May 30 '17 at 06:46

Stavros Avramidis · Answer 1 · 2017-05-30T08:15:18.880

0

This works for me: i added an int() in the second parameter of if, you were comparing stings(your dic values) with integers, which in python 2 as pointed in the comments always returns true.

enrollments= [{u'account_key': u'448', u'cancel_date': u'2014-11-10', u'days_to_cancel': u'5', u'is_canceled': u'True', u'is_udacity': u'True', u'join_date': u'2014-11-05', u'status': u'canceled'},
{u'account_key': u'448', u'cancel_date': u'2015-01-27', u'days_to_cancel': u'10', u'is_canceled': u'True', u'is_udacity': u'True', u'join_date': u'2015-01-27', u'status': u'canceled'}]

paid_students=[]
for students in enrollments:
    if students['days_to_cancel']==None or int(students['days_to_cancel'])>7:
        paid_students.append(students)

print len(paid_students)

edited May 30 '17 at 08:15

answered May 30 '17 at 06:50

Stavros Avramidis

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Do explain what you changed and why. Without an explanation this is not a helpful answer. – Martijn Pieters May 30 '17 at 06:53
@MartijnPieters added – Stavros Avramidis May 30 '17 at 07:15
1

So *why* did you add `int()`? Why does it add all elements to `paid_students` otherwise? (Yes, I already know the answer, but future visitors won't be able to get that information from your post). – Martijn Pieters May 30 '17 at 07:28
@MartijnPieters i hope my answer is complete now – Stavros Avramidis May 30 '17 at 08:16

Why is all the data getting appended to the list

1 Answers1