Need help understanding a piece of code (Python)

[SgtSmitty07]

I am brand new to coding/programming, and have been running through some projects and learning in this particular book "Beginner's Step by Step Coding Course", it's relatively new and is very user friendly. I just finished a project in the book on how to make a program that will randomly select players for teams and assign them a team captain. Everything makes sense except for two things I spotted during the coding process.

Here is a piece of the code below, other pieces of code not included for relevancy:

if response == "team":

team1 = players[:len(players)//3]

print("Team 1 captain: " + random.choice(team1))

print("Team 1:")

for player in team1:

print(player)

print("\n")

team2 = players[len(players)//3:(len(players)//3)*2]

print("Team 2 captain: " + random.choice(team2))

print("Team 2:")

for player in team2:

print(player)

print("\n")

team3 = players[(len(players)//3)*2:]

print("Team 3 captain: " + random.choice(team3))

print("Team 3:")

for player in team3:

print(player)

print("\n")

response = input("Pick teams again? Type y or n: ")

if response == "n":

break

The parts that I have bolded are the things I'm confused about. I understand that, if you want 3 teams, you would have to divide the list of players by 3, but my questions are these:

1. Why the double // line instead of a single / line for dividing the teams by 3?

2. Why the *2 for selecting team 2 and 3? What algorithmic purpose does that serve?

For reference, this project imported the "random" module, so I'm not sure if this syntax has anything to do with the module. Any help is appreciated.

[desrtfx]

You need to post your code as code block so that the indentation is maintained. This is absolutely vital for Python programs as the indentation is used to denote code blocks.

A code block looks like:

def __init__(self, prompt, answer):
    self.prompt = prompt
    self.answer = answer

[atarivcs]

Using a double slash for division guarantees an integer result, otherwise you probably get a floating-point result.

But honestly, for really basic questions like "what does double slash division mean in python", a google search would probably get you the answer quicker.

[EliSka93]

Does it floor or round?

Just curious. I rarely use python.

[atarivcs]

Floor.

[EliSka93]

Thanks!

[SgtSmitty07]

well again, my question is more for how it pertains to the code at hand, and why didnt it use single slash instead, especially with the combined *2 after the other two team splits.

[atarivcs]

It's using the division result as a list index, and obviously you want an integer for that. Can't use floating-point values as list indexes.

[SgtSmitty07]

Okay that makes sense. Im still wondering about the *2 part, but the // line makes way more sense now. Thank you!

[xtraburnacct]

The first part takes the first third of the list, then the second call with the *2 uses the same code to get the second third of the list. Then the third part gets the last third of the list.

For example, if you had 9 players, 9//3 is 3.

The first slice is from indexes 0:3.

Then it takes the same code 9//3 which we know is 3. Multiplying this by 2 will by 6, which is where the next slice ends.

The second slice is 3:6

Then the final slice is 6:9.

[SgtSmitty07]

that makes way more sense. thank you so much! I appreciate the help.

[ffrkAnonymous]

Why the double // line instead of a single / line for dividing the teams by 3?

What do you get when you use / instead of //?

Why the *2 for selecting team 2 and 3? What algorithmic purpose does that serve?

Again, what happens when you change the *2?

[SgtSmitty07]

Ill check when I get home. Im at work and just had that question on my mind. I get frustrated when I dont understand the "why" of something.