CODEWITHSUNDEEP
pythonarrayslambdatuplesmin
Sam333
Sam333

Reputation: 341

Find the index of minimum value of tuple pairs in Python

With a list of tuple pairs n=[(266, 116), (81, 296), (148, 115), (324, 303)] I am trying to efficiently find the index of the left-most points. Currently, my code looks like this:

min_index = 0
for i in range(1,len(n)): 
     if points[i][0] < points[min_index][0]: 
            minIndex = i

but to me this does not look efficient. I also found a solution using lambda function, which might at least look more appealing (idk about the time complexity here of the min function)

min(n, key = lambda t: t[0])

but this gives me the actual coordinates, not the index which I want. How can I change the lambda function to give me the actual index, and is there any better solution in terms of time complexity? Thank you

Upvotes: 0

Views: 577

Answers (2)

Krishna Chaurasia
Krishna Chaurasia

Reputation: 9580

You could also enumerate in the lambda part to get both the index and the value as:

n = [(266, 116), (81, 296), (148, 115), (324, 303)]
min_index, min_value = min(enumerate(n), key = lambda n: n[1][0])
print(min_index, min_value)   # 1 (81, 296)

Upvotes: 0

Djaouad
Djaouad

Reputation: 22776

Use range(len(n)) in the min instead of n:

>>> min(range(len(n)), key = lambda i: n[i][0])
1

Note: the loop approach is not in anyway inefficient since there is no apparent pattern in the data, so you can't, for instance, use a dichotomy approach (such as binary search), and the min does almost the same thing, it's just preferred sometimes because it is built-in, more concise, and less prone to errors.

Upvotes: 1

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