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pythonlist
Flodude
Flodude

Reputation: 275

How to get a specific number position on the list?

Is there a method to retrieve the number position in the list? For example, in the following code, can we get the maximum number position?

a = [1, 2, 10, 5]
    
print(index_max(a))
# 2

Upvotes: 0

Views: 910

Answers (5)

Alain T.
Alain T.

Reputation: 42143

You could use the index method:

a.index(max(a)) # 2

Or, if your list is long and you don't want to go through it twice, you can use the key parameter of the max function:

max(range(len(a)),key=lambda i:a[i]) # 2

This finds the maximum index (from range(len(a))) but uses an indirection to determine how to compare the index. So the comparison is based on the value at each index instead of the index itself. The result is the index that has the highest value.

for details on the max() function see: https://docs.python.org/3/library/functions.html#max

Upvotes: 2

Developer
Developer

Reputation: 29

Python has an inbuilt function called index(), which can be used to obtain the index position of an element in a list. In this instance, you may write a.index(max(a)).

Upvotes: 0

dawg
dawg

Reputation: 103884

If you have more than one value that might be the max you can use enumerate:

a = [1, 2, 10, 5, 10, 6]

>>> [i for i,x in enumerate(a) if x==max(a)]
[2, 4]

Or, if you want the value included:

>>> [(i,x) for i,x in enumerate(a) if x==max(a)]
[(2, 10), (4, 10)]

Upvotes: 0

kostas_math
kostas_math

Reputation: 80

You can try

>>> print(a.index(max(a)))
2

So you are priting the index-position in list of the maximum number

Upvotes: 0

Francisco
Francisco

Reputation: 11486

You can use the index method:

a.index(max(a))

Another possibility, is using enumerate:

>>> max(enumerate(a), key=operator.itemgetter(1))
(2, 10)

Upvotes: 0

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