Python function that counts negative integers using arbitrary number of parameters

Question

Python newbie here, I need help with working with function with arbitrary number of parameters.

I want to implement a function that can take an arbitrary number of parameters, and counts negative integers. I want to try the negative_counter function on the following list of numbers 4,-3,5,6,-7

See my attempt (not sure what I am doing wrong)

def negative_counter(*args):
    # setting the negative count to 0
    neg_count = 0
    # iterating through the parameters
    for x in args:
    # negative numbers are less than 0
        if args < 0:
    # adding 1 to negative number
            neg_count = neg_count + 1
            return neg_count

# driver code 
negative_counter([4,-3,5,6,-7]) 

#Desired output should return 2 since -3 and -7 are the negative integers

Please publish your code as you respond. Thanks

Answer 1

There are 2 problems with your code. First, it should be if x < 0 instead of if args < 0 because x is an element in args. Second, you have a return inside the loop, so it ends the function after increasing the neg_count by one.

This code may be better and shorter;)

only_neg = [num for num in args if num < 0]
neg_count = len(only_neg)

or

neg_count = sum(1 for i in args if i < 0)

Answer 2

There are a couple issues with your code:

• You've specified that the function take a single variadic argument, as discussed in the Arbitrary Arguments List documentation . So, args ends up being a list with one element, the list you're passing in your driver.
• You need to perform a comparison against x instead of args .

Here are examples that show demonstrate working with variadic arguments as well as unpacking argument lists , along with a simplified implementation:

def negative_counter(*args):
    neg_count = 0
    for x in args:
        if x < 0:
            neg_count = neg_count + 1
    return neg_count

def negative_counter_list(num_list):
    neg_count = 0
    for x in num_list:
        if x < 0:
            neg_count = neg_count + 1
    return neg_count

def negative_counter_simplified(*args):
    return len([x for x in args if x < 0])

numbers = [4, -3, 5, 6, -7]

# use "*numbers" to unpack the list
print(negative_counter(*numbers))

# use the function that actually expects the list
print(negative_counter_list(numbers))

# use the simplified implementation, once again unpacking the list
print(negative_counter_simplified(*numbers)

Output:

$ python3 test.py
2
2
2