Return first N key:value pairs from dict

Question

Consider the following dictionary, d:

d = {\'a\': 3, \'b\': 2, \'c\': 3, \'d\': 4, \'e\': 5}

I want to return the first N key:value pairs f

Answer 1

This depends on what is 'most efficient' in your case.

If you just want a semi-random sample of a huge dictionary foo, use foo.iteritems() and take as many values from it as you need, it's a lazy operation that avoids creation of an explicit list of keys or items.

If you need to sort keys first, there's no way around using something like keys = foo.keys(); keys.sort() or sorted(foo.iterkeys()), you'll have to build an explicit list of keys. Then slice or iterate through first N keys.

BTW why do you care about the 'efficient' way? Did you profile your program? If you did not, use the obvious and easy to understand way first. Chances are it will do pretty well without becoming a bottleneck.