In Python can you pass two arguments to a function where one argument is extrapolated from the other-CodePudding

I'm writing a recursive binary-search function in Python. My code looks like common examples where the function accepts:

(a) a list of numbers; (b) the search term; (c) the length of the list for the initial location of the right pointer; and (d) a default argument of 0 for the left pointer.

Do I have to pass both a list of numbers (a) and also the length of the list (c)? Can't I make a default argument that automatically computes the length of argument (a)?

MWE:

def binarySearchRecur(nums, target, high, low=0):
    if high - low == 1:
        return "not found"
    elif nums[(high   low) // 2] < target:
        low = (high   low) // 2
        return binarySearchRecur(nums, target, low, high)
    elif nums[(high   low) // 2] > target:
        high = (high   low) // 2   1
        return binarySearchRecur(nums, target, low, high)
    return f"index at: {(low   high) // 2}"


target = 16
nums = [x for x in range(20)]
print(binarySearchRecur(nums, target, len(nums)-1))

In the code above I'd like to call the function the first time using only nums and target.

CodePudding user response：

Could you simply do something like this?

def binarySearchRecur(nums, target, high=None, low=0):
   if high is None:
      high=len(nums)
...

This way if you only input the list and the target, the first thing the function will do is to infer "high" from the list.