编程新手求助：如何实现Python数组中负数求和？

Hey there! Let's get your code working to sum all the negative numbers in your array. I'll break down the issues in your current code and show you a corrected version, plus a more concise alternative.

Issues in Your Current Code #

• Incomplete function definition: Your def ma line is cut off, and the function name ArraySumNegative is placed incorrectly. Proper function definitions follow the format def function_name(parameters):.
• Missing loop logic: You need to iterate over each element in the array to check if it's negative—right now there's no code to go through each value.
• Syntax error in condition: if i<0 is missing a colon (:) at the end, which is required for Python conditional statements.
• No accumulator variable: There's nothing to keep track of the total sum of negative numbers as you find them.
• Invalid function call: printsum(myvals) isn't a valid Python function; you need to call your defined function and print its result.

Corrected Complete Code #

Here's a fixed version that works as intended:

# Define the function to calculate sum of negative numbers
def ArraySumNegative(arr):
    # Initialize a variable to hold the total sum of negatives
    total_negative = 0
    # Loop through each number in the input array
    for num in arr:
        # Check if the number is negative
        if num < 0:
            # Add the negative number to the total
            total_negative += num
    # Return the final sum
    return total_negative

# Test the function with your sample array
myvals = [1, -1, 2, -3.5, 8.5]
# Call the function and store the result
result = ArraySumNegative(myvals)
# Print the result
print("Sum of negative numbers:", result)

How This Works #

1. Function Definition: ArraySumNegative(arr) takes an array arr as input.
2. Accumulator: total_negative starts at 0 and will hold the sum of all negative numbers.
3. Loop: for num in arr iterates over every element in the array, assigning each element to num.
4. Condition Check: if num < 0 checks if the current number is negative. If yes, it adds the number to total_negative.
5. Return Result: The function returns the final sum, which we then print.

A More Concise Version #

If you want to write this more succinctly, you can use Python's built-in sum() function with a generator expression to filter negatives:

def ArraySumNegative(arr):
    return sum(num for num in arr if num < 0)

myvals = [1, -1, 2, -3.5, 8.5]
print("Sum of negative numbers:", ArraySumNegative(myvals))

This does the same thing in fewer lines—sum() calculates the total of all numbers in the generator expression, which only includes values from arr that are negative.

内容的提问来源于stack exchange，提问作者James