CS105: Introduction to Python

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. To traverse the keys in sorted order, you can use the built-in function sorted:

>>> for key in sorted(h):
...     print(key, h[key])
a 1
o 1
p 1
r 2
t 1