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Python

Posted by Mark Libario
Mark Libario
9,003 Points

OrderedDict question.

Hello,

Im confused how an OrderedDict that was converted to a list becomes a class dict again when I do for loop for each item.

Example:

def csv_to_list ():
    with open("students.csv", newline="") as csv_file:
        csv_reader = csv.DictReader(csv_file)
        item_list = list(csv_reader)
        return csv_list

def sort_students(students):
    for student in students:
        print(type(student))
#Meaning I can use dict methods when I use for loops.

def sort_students(students):
    smart = []
    for student in students:
        if student["IQ"] == "HIGH":
            smart.append(student)
#Now it is appended back to a list, it becomes a list again.

How can I access that list again like a dictionary if lets say there are more than 2 key,values inside? If I try to do a dict(smart), it gives me an error saying expected values is 2 only. something like this.

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,468 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,468 Points

It's no obvious how you are calling these functions, but I think I see the confusion.

Creating a list object from an OrderedDict object results in a list of the dictionary keys:

OrderedDict
>>> d = OrderedDict()
>>> d
OrderedDict()
>>> d[1]="a"
>>> d
OrderedDict([(1, 'a')])
>>> d[2]="b"
>>> d
OrderedDict([(1, 'a'), (2, 'b')])
>>> cvs_list = list(d)
>>> type(cvs_list)
<class 'list'>
>>> cvs_list
[1, 2]

A for loop operates on any container. If the container is a dict then a list of the dict keys are looped over:

for item in some_dict:

# is equivalent to

for item in some_dict.keys():

Post back if you need more help. Good luck!!!