python - In dictionary where keys are numbers, how to find key which is smaller but the most near to given number?

Question

In dictionary where keys are numbers, how to find key which is smaller then a given number but the most near to given number ?

I can sort list of keys in ascending and then while but is there more python way to do this ( I am from Java and this is Java approach)

example:
{{1:9}, {6:7}, {5:45}, {3:90}}
for given number 4 result is 3

Answer 1

我认为 Vicktor Kerkez 的回应的变体是最清楚的：

d = {1:9, 6:7, 5:45, 3:90}
print max(k for k in d if k < 4)

该k for k in d if k < 4部分遍历键并仅返回小于 4 的键。然后max()返回其中最大的键。