Can anyone please explain to me what is wrong with the following code

Question

def search(num_list, find):
    while True:
        if not num_list:
            return "Not in list"
        else:
            i = int(len(num_list) // 2)
            if int(num_list[i]) == find:
                return i
            elif int(num_list[i]) > find:
                num_list = (lambda x: x < num_list[i], num_list)
            elif int(num_list[i]) < find:
                num_list = (lambda x: x > num_list[i], num_list)


checkList = [2, 5, 8, 18, 22, 35, 45, 72]
element = int(input("Enter number to be found: "))
print(search(checkList, element))

The following error message occurs when i try to run it with any number:

Traceback (most recent call last):
  File "/home/rahul/PycharmProjects/binSearch/main.py", line 17, in <module>
    print(search(checkList, element))
  File "/home/rahul/PycharmProjects/binSearch/main.py", line 7, in search
    if int(num_list[i]) == find:
TypeError: int() argument must be a string, a bytes-like object or a number, not 'list'

So I am trying to make a python binary search algorithm for class and thought this would work fine. I have no idea why this is not working and would love an expert opinion

Answer 1

The reason you are getting this error, is your lambda function is in a tuple of a function and a list. So just looking at that part:

num_list = [2, 5, 8, 18, 22, 35, 45, 72]
i = 5
num_list = (lambda x: x < num_list[i], num_list)

print(num_list)

result:

(<function <lambda> at 0x107a170e0>, [2, 5, 8, 18, 22, 35, 45, 72])

which is the memory address of the lambda function, and a list, which you end up passing to int() , giving the error that you see.