New to python, help please with reading this lines-CodePudding

square = {2: 4, -3: 9, -1: 1, -2: 4}
key1 = max(square)
print(key1) # 2
key2 = max(square, key = lambda k: square[k])
print(key2) # -3
key3 = square[key2]
print(key3) # 9

Q1: sorry if this question seems irrelevant but, how does square[k] works, I can't get the logic behind it every time I remove K, the answer would be the same as key1 Q2: How does the logic works with key3 resulting to 9

THANK YOU IN ADVANCE!!!

CodePudding user response：

The second argument to max is an ordering function that extracts the value to order by. Thus, max(square, key = lambda k: square[k]) returns the key of square that has the greatest corresponding value.

CodePudding user response：

In this instance, k is referring to the key in the dictionary square.

Dictionaries are made up of key:value pairs, which you can see in the declaration of square in the first line.

If we want a specific value from a dictionary, we need to reference it's key. So if we want to print 4 from our dictionary, we need to feed in the key 2.

So the following code would print '4':

square = {2: 4, -3: 9, -1: 1, -2: 4}
k = 2
print(square[k])