Python – Efficient way to find the largest key in a dictionary with non-zero value

dictionarypython

I'm new Python and trying to implement code in a more Pythonic and efficient fashion.
Given a dictionary with numeric keys and values, what is the best way to find the largest key with a non-zero value?

Thanks

Best Answer

Something like this should be reasonably fast:

>>> x = {0: 5, 1: 7, 2: 0}
>>> max(k for k, v in x.iteritems() if v != 0)
1

(removing the != 0 will be slightly faster still, but obscures the meaning somewhat.)

Related Solutions

C# – How to sort a dictionary by value

Use LINQ:

Dictionary<string, int> myDict = new Dictionary<string, int>();
myDict.Add("one", 1);
myDict.Add("four", 4);
myDict.Add("two", 2);
myDict.Add("three", 3);

var sortedDict = from entry in myDict orderby entry.Value ascending select entry;

This would also allow for great flexibility in that you can select the top 10, 20 10%, etc. Or if you are using your word frequency index for type-ahead, you could also include StartsWith clause as well.

Python – Calling a function of a module by using its name (a string)

Assuming module foo with method bar:

import foo
method_to_call = getattr(foo, 'bar')
result = method_to_call()

You could shorten lines 2 and 3 to:

result = getattr(foo, 'bar')()

if that makes more sense for your use case.

You can use getattr in this fashion on class instance bound methods, module-level methods, class methods... the list goes on.

Best Answer

Related Solutions

C# – How to sort a dictionary by value

Python – Calling a function of a module by using its name (a string)

Related Topic