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2.3: Looping and Dictionaries

  • Page ID
    15419
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    If you use a dictionary in a for statement, it traverses the keys of the dictionary. For example, print_hist prints each key and the corresponding value:

    def print_hist(h):
        for c in h:
            print c, h[c]
    

    Here’s what the output looks like:

    >>> h = histogram('parrot')
    >>> print_hist(h)
    a 1
    p 1
    r 2
    t 1
    o 1
    

    Again, the keys are in no particular order.

    Exercise \(\PageIndex{1}\)

    Dictionaries have a method called keys that returns the keys of the dictionary, in no particular order, as a list.

    Modify print_hist to print the keys and their values in alphabetical order.


    This page titled 2.3: Looping and Dictionaries is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Allen B. Downey (Green Tea Press) .

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