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Python Python Collections (2016, retired 2019) Dictionaries Dictionary Iteration

Hussein Amr
Hussein Amr
2,461 Points
Posted by Hussein Amr
Hussein Amr
2,461 Points

Didn't get how printing the minutes of the courses works 

for course in course_minutes:
      print(course_minutes[course])

How does that print the values exactly?

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

Let's look at the two statements. First:

for course in course_minutes:

Says:

  • treat course_minutes as an iterable object
  • take each item from the iterable and assign it to the variable course
  • then run the loop code using this new value of course

When a dict is used in the context of an iterable, it will respond with a list of the dictionary keys. So course will contain the various course names.

      print(course_minutes[course])

Says:

  • use the course defined by the for loop as the key to the dict course_minutes
  • look up the value, and print it

Hope this helps. Post back if you need more help. Good Luck!!

Idan shami
Idan shami
13,251 Points
Idan shami
Idan shami
13,251 Points

I don't understand why if the course defined as a key it means to look up the value, why it is saying that, i just cannot understand it.

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

It is the square brackets around course that designates it semantically as a dict key In dict notation, an item is looked up using the form some_dict[key]. Otherwise course is just a string object.