CODEWITHSUNDEEP
pythonpython-3.xlistnested-lists
Tim Stack
Tim Stack

Reputation: 3248

Get max value and index of max value from last item in nested lists

I have a list of nested lists:

scoring_matrix = [[1, 2, 7], [3, 5, 2], [2, 2, 7]]

I am trying to get the max value from all last items in the nested lists, together with the index/indices of the nested list(s) with that max value. All nested lists are of equal length.

In this example:

item     output (value, index)
2        [7, [0, 2]]

I also needed to get the highest value and index/indices for the last nested list, which I worked out:

max_last_list = [index for index, item in enumerate(scoring_matrix[-1]) if item == max(scoring_matrix[-1])]

I am attempting to rewrite this line to make it work on my problem, but I can't find out how to do it.

The solution cannot make use of non-built in modules

Upvotes: 0

Views: 311

Answers (6)

Max Tet
Max Tet

Reputation: 755

Try to make your solution readable. Instead of a clever one-liner, more code with clear variable names is often easier to comprehend.

I would first calculate the maximum and in a second step find the indices for that maximum.

scoring_max = max(l[-1] for l in scoring_matrix)
indices = [i for i, sublist in enumerate(scoring_matrix) if sublist[-1] == scoring_max]
return [scoring_max, indices]

The solution to your second problem is very similar.

last_sublist = scoring_matrix[-1]
list_max = max(last_sublist)
indices = [i for i, val in enumerate(last_sublist) if val == list_max]

Upvotes: 1

azro
azro

Reputation: 54148

Based on my first answer, and other answers below :

  1. Compute the end's max and find it in the sublists

    # Find the max of the ends value
max_end = max(map(lambda x: x[-1], scoring_matrix))
# Find the sublist whe the last if the overall max
indexes = [index for index, item in enumerate(scoring_matrix) if item[-1] == max_end]
# Group result
result = [max_end, indexes]

print(result)

  2. Keep the ends together and work on them

    # Put all ends value in a list
ends = list(zip(*scoring_matrix))[2]
# Iterate over the ends to find the overall max
indexes = [i for i, v in enumerate(ends) if v == max(ends)]
# Group result
result = [max(ends), indexes]

print(result)

Upvotes: 4

Thierry Lathuille
Thierry Lathuille

Reputation: 24232

Keep it simple, get the max, then create the list of indices:

scoring_matrix = [[1, 2, 7], [3, 5, 2], [2, 2, 7]]

m = max(sublist[2] for sublist in scoring_matrix)
out = [m, [i for i, sub in enumerate(scoring_matrix) if sub[2] == m]]

print(out)
#[7, [0, 2]]

Upvotes: 1

Bharath M Shetty
Bharath M Shetty

Reputation: 30605

You can also try this : 

maxi = max(sum(scoring_matrix,[]))
res = [maxi,[n for n,i in enumerate(scoring_matrix) if maxi in i]]

Output: 

[7, [0, 2]]

Upvotes: 1

U13-Forward
U13-Forward

Reputation: 71570

Try using the below code:

l = list(zip(*scoring_matrix))[2]
print([max(l), [i for i, v in enumerate(l) if v == max(l)]])

Output:

[7, [0, 2]]

Upvotes: 3

Vishnudev Krishnadas
Vishnudev Krishnadas

Reputation: 10960

Adding to @U10-Forward's answer,

l = list(zip(*scoring_matrix))[2]
print([max(l), [i for i, v in enumerate(l) if v == max(l)]])

Upvotes: 1

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