Is there a better way to print these key-value pairs?

Question

So this is some code I did working exercise 6-9 of Chapter 6 in Python Crash Course book.

favorite_places = {
'joe': {
    'paris': 'france',
    'hamburg': 'germany',
    'cairo': 'egypt',
    },
'anna': {
    'tripoli': 'libya',
    'tokyo': 'japan',
    'moskva': 'russia',
    },
'henry': {
    'sydney': 'australia',
    'quebec': 'canada',
    'rio de janeiro': 'brazil',
    }
}

for person, places in favorite_places.items():
    print(person.title() + "'s favorite places are: ")
    places = places.items()
    for place in places:
        print(place[0].title() + " in " + place[1].title() + ".")
    print("\n")

Then the output is like this:

Joe's favorite places are:
Cairo in Egypt.
Hamburg in Germany.
Paris in France.

Is there a way to just get the key-value from the places variable and print it the same way I did but without converting places to a list? I think it's a bit messy like this...

Jean-François Fabre · Answer 1 · 2016-10-30T14:00:50.330

3

by doing this

places = places.items()

in python 3 you're not converting to a list but you access an iterator which yields the key,value pair so it's the best way of doing it.

(python 2 equivalent is iteritems, in python 2 items returns a list of couples but the behaviour has changed in python 3)

(what surprises me most is 1) your indentation and 2) you'd be better off writing directly that without using an array or a temp variable (unpacking the couples directly in 2 variables is more elegant, and use format as stated in the comments which is more elegant & performant)

for town,country in places.items():
    print("{} in {}.".format(town.title(),country.title())
print("\n")

edited Oct 30 '16 at 14:00

answered Oct 30 '16 at 12:15

Jean-François Fabre

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that's some silly mistake indenting.... But yeah I understand what you pointed out and thanks for answering. :) – Oct 30 '16 at 12:26
1

You should not be adding the strings together. That eats CPU and it's not pythonic! Instead use `%s` or `.format` which is more popular for python3 – Stam Kaly Oct 30 '16 at 13:52
while we're trying to be the most pythonic possible, you're right. Just copied the OP's code without changing it. Edited. – Jean-François Fabre Oct 30 '16 at 14:01

Stam Kaly · Answer 2 · 2016-10-30T14:29:06.390

1

Format is now in fashion for me so here's another cool way of doing this:

for name, places in favorite_places.items():
    print("{}'s favorite places are:".format(name.capitalize()))
    for city, country in places.items():
        print("{} in {}.".format(city.capitalize(), country.capitalize()))
    print('\n')

edited Oct 30 '16 at 14:29

answered Oct 30 '16 at 13:50

Stam Kaly

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I get what you're trying to say, and it's valid point, however your code doesn't work – GingerPlusPlus Oct 30 '16 at 14:00
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what you should avoid even if it worked is the need to hash the key at each iteration. you'll iterate through all the dictionary so better use `items()` – Jean-François Fabre Oct 30 '16 at 14:02
...and tuple unpacking, that'd also make your code more readable: `for name, places in favorite_places.items()`, `for country, city in place` – GingerPlusPlus Oct 30 '16 at 14:03
Thanks guys, I haven't worked with dictionaries a lot before – Stam Kaly Oct 30 '16 at 14:14

score 0 · Answer 3 · answered Oct 30 '16 at 13:38

0

A slightly shorter way (still using list though) would be:

for person in favorite_places:
    print("%s's favorite places are: " %person.title())
    [print('%s in %s.' %(i.title(),z.title())) for i,z in favorite_places[person].items()]
    print('\n')

answered Oct 30 '16 at 13:38

spyrostheodoridis

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Is there such a rule somewhere that I missed? – spyrostheodoridis Oct 30 '16 at 13:47
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[Is it Pythonic to use list comprehensions for just side effects?](http://stackoverflow.com/q/5753597/3821804) – GingerPlusPlus Oct 30 '16 at 13:50
Cool, now I get it. Thanks! – spyrostheodoridis Oct 30 '16 at 13:57
1

a generator comprehension would be slightly better performance-wise, but cryptic and doesn't help readability. – Jean-François Fabre Oct 30 '16 at 14:03
1

Sorry gencomps which are not iterated through will do nothing so my previous comment is wrong about that – Jean-François Fabre Oct 30 '16 at 14:08
1

@Jean: well, you could pass it to `consume` from `more-itertools`. – GingerPlusPlus Oct 30 '16 at 14:50
@GingerPlusPlus since it's only a recipe, just doing that would do it `collections.deque(iterator, maxlen=0)`. It's beginning to become a bit far fetched, though. – Jean-François Fabre Oct 30 '16 at 15:56

Is there a better way to print these key-value pairs?

3 Answers3