CODEWITHSUNDEEP
pythonpython-3.xlist
Wan-Hew Tran
Wan-Hew Tran

Reputation: 43

Choosing list with the largest value

I have two lists of numbers and I want a function to return the list with the largest number i.e with two lists [1,2,3,9] and [4,5,6,7,8], the function should return [1,2,3,9].

I know for a fact that this works:

a = [1,2,3,9]
b = [4,5,6,7,8]
ans = [_ for _ in [a,b] if max(_) == max((max(a),max(b)))][0]

I know that there is:

a = [1,2,3,9]
b = [4,5,6,7,8]
if max(a)>max(b):
    ans = a
else:
    ans = b

But is there a more efficient one or two line solution?

Upvotes: 4

Views: 157

Answers (4)

Jon Kiparsky
Jon Kiparsky

Reputation: 7743

This would work

max([a,b], key=max)

The trick here is to know that the max function can be applied to objects which do not have a natural numerical interpretation, using a key function.

Upvotes: 0

Alain T.
Alain T.

Reputation: 42143

The max function allows you to specify a key. You can supply the two lists as a list of lists to max() and use max as the key function. This will give yout the result with a very compact statement:

a = [1,2,3,9]
b = [4,5,6,7,8]
result = max([a,b],key=max)

Upvotes: 3

Jurgen Strydom
Jurgen Strydom

Reputation: 3930

I would recommend numpy or pandas but your solution looks good to be honest.

Here is a numpy example (typing on phone so not tested) 

npa = np.array(a) 
npb = np.array(b)

max_array = None
total_max = 0  # or -np.inf if you want to deal with negative numbers too
for k in [npa, npb]:
    if k.max() > total_max:
         max_array = k

Upvotes: 0

Sheldore
Sheldore

Reputation: 39042

How about using the following without any for loop. Just compare the max of lists

a = [1,2,3,9]
b = [4,5,6,7,8]
ans = (a if max(a) > max(b) else b)
# [1, 2, 3, 9]

Upvotes: 9

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