Python compact radix sort of numbers

gistfile1.py

class RadixSort:
    def radix_sort(self, nums):
        """
        Input an number list and return an sortd list
        Type: [Int] -> [Int]
        """
        max_len = max(map(lambda x: len(str(x)), nums))
        
        tmp, base = 1, 10
        for i in range(max_len):
            buckets = [[] for i in range(10)]
            for num in nums:
                buckets[num / tmp % base].append(num)
            
            nums = [x for bucket in buckets for x in bucket]
            tmp = tmp * 10
        
        return nums