在列表列表中查找最小的数字

Question

I have the following data set:

data = 
{
a:[1,2,3]
b:[3,4,5]
c:[5,6,7]
...
}

And I am trying to find the smallest number from the index 1 from all the lists.

The only way I could imagine doing it would be this:

num = []
index_number = 1

for var in data:
  num.append(data.get(var)[index_number])
return min(num)

But i think this is not a very good solution.

Also I will have to find the key that corresponds to the value that i just found.

Is there a good solution that i am not aware of?

Answer 1

data = {'a': [1, 2, 3], 'b': [3, 4, 5], 'c': [5, 6, 7]}
min_key = min(data,key=lambda key:min(data[key]))

this tells python you want the "min" value of the data dict, we will use the minimum of each keys list of values as our comparison key in finding the min

Answer 2

A simple comprehension may do the trick:

>>> data = {'a': [1, 2, 3], 'b': [3, 4, 5], 'c': [5, 6, 7]}
>>> index_number = 1
>>> min(((k, v[1]) for k, v in data.items()), key=lambda x: x[1])
('a', 2)

If you need only the minimum value, you may use a simpler approach

>>> data = {'a': [1, 2, 3], 'b': [3, 4, 5], 'c': [5, 6, 7]}
>>> index = 1
>>> min(v[index] for v in data.values())
2