CODEWITHSUNDEEP
python
Alex Kulinkovich
Alex Kulinkovich

Reputation: 4778

Logic with dictionary and list

I executed this snippet: 

lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [ 88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}
alice = {
    "name": "Alice",
    "homework": [100.0, 92.0, 98.0, 100.0],
    "quizzes": [82.0, 83.0, 91.0],
    "tests": [89.0, 97.0]
}
tyler = {
    "name": "Tyler",
    "homework": [0.0, 87.0, 75.0, 22.0],
    "quizzes": [0.0, 75.0, 78.0],
    "tests": [100.0, 100.0]
}

students=[lloyd, alice, tyler]

for i in students:
    for f in i:
        print i[f]

I don't understand why output is the next:

[88.0, 40.0, 94.0]
[75.0, 90.0]
Lloyd
[90.0, 97.0, 75.0, 92.0]
[82.0, 83.0, 91.0]
[89.0, 97.0]
Alice
[100.0, 92.0, 98.0, 100.0]
[0.0, 75.0, 78.0]
[100.0, 100.0]
Tyler
[0.0, 87.0, 75.0, 22.0]

Why it happens so? Where I can find docs for that? Could someone give me short explanation for logic of output?

Upvotes: 1

Views: 1341

Answers (3)

Eric
Eric

Reputation: 97601

You can easily fix this with a changed loop:

for student in students:
    for key in ["name", "homework", "quizzes", "tests"]:
        print student[key]

Namedtuples might be a better match here:

from collections import namedtuple
Student = namedtuple('Student', ["name", "homework", "quizzes", "tests"])

students = [
    Student(name="Lloyd",
            homework=[90.0, 97.0, 75.0, 92.0],
            quizzes=[ 88.0, 40.0, 94.0],
            tests=[75.0, 90.0])
    Student(name="Alice",
            homework=[100.0, 92.0, 98.0, 100.0],
            quizzes=[82.0, 83.0, 91.0],
            tests=[89.0, 97.0])
    Student(name="Tyler",
            homework=[0.0, 87.0, 75.0, 22.0],
            quizzes=[0.0, 75.0, 78.0],
            tests=[100.0, 100.0])
]

Upvotes: 2

Tomasz Łazarowicz
Tomasz Łazarowicz

Reputation: 435

Regular dictionaries are not ordered.

It is best to think of a dictionary as an unordered set of key: value pairs

Source

If you really need an ordered dictionary, look into OrderedDict.

Upvotes: 6

Marcelo Cantos
Marcelo Cantos

Reputation: 185892

Dictionary keys don't have a defined ordering. {'a':1,'b':2} and {'b':2,'a':1} are considered equal, and they print out the same way:

>>> {'a':1, 'b':2}
{'a': 1, 'b': 2}
>>> {'b':2, 'a':1}
{'a': 1, 'b': 2}

Note, also, from your own experience, that you can't assume they'll come out in alphabetical order.

Upvotes: 6

Related Questions