Python Add Comma Into Number String

Question

Using Python v2, I have a value running through my program that puts out a number rounded to 2 decimal places at the end:

like this:

print (\"Total          


        

Answer 1

Started learning Python about 5 hours ago, but I think I came up with something for integers (sorry, couldn't figure out floats). I'm in high school, so big chance the code could be way more efficient; I just made something from scratch that made sense to me. If anyone has any ideas on how to improve with ample explanation of how it works, let me know!

# Inserts comma separators
def place_value(num):
    perm_num = num  # Stores "num" to ensure it cannot be modified
    lis_num = list(str(num))  # Makes "num" into a list of single-character strings since lists are easier to manipulate
    if len(str(perm_num)) > 3:
        index_offset = 0  # Every time a comma is added, the numbers are all shifted over one
        for index in range(len(str(perm_num))):  # Converts "perm_num" to string so len() can count the length, then uses that for a range
            mod_index = (index + 1) % 3  # Locates every 3 index
            neg_index = -1 * (index + 1 + index_offset)  # Calculates the index that the comma will be inserted at
            if mod_index == 0:  # If "index" is evenly divisible by 3
                lis_num.insert(neg_index, ",")  # Adds comma place of negative index
                index_offset += 1  # Every time a comma is added, the index of all items in list are increased by 1 from the back
        str_num = "".join(lis_num)  # Joins list back together into string
    else:  # If the number is less than or equal to 3 digits long, don't separate with commas
        str_num = str(num)
    return str_num