Is there a way to pull corresponding items from different lists in python?

Question

I'm trying to create a program that will keep track of your party and their health in a tabletop RPG. The best way I can think of so far is to have two separate lists, one with the party members and one with their health, so that when you display the party, it will run a code that looks something like this:

for Member in Party:
    print(str(Member) + ":", str(Health), "HP")

Is there a way to pull the corresponding HP for each member from the different lists?

Or a dictionary with the key being the player and the value being the health? — dfundako, Jul 23 '18 at 17:27
You can use `zip` for this: `for Member, Health in zip(Party, PartyHealth):`. However, it’s probably better to use a single list of member objects that know their name and health, or at least a single list of `(name, health)` tuples or lists, instead of two separate lists here. — abarnert, Jul 23 '18 at 17:36
Possible duplicate of [How to iterate through two lists in parallel?](https://stackoverflow.com/questions/1663807/how-to-iterate-through-two-lists-in-parallel) — Sнаđошƒаӽ, Jul 23 '18 at 17:51

swhat · Answer 1 · 2018-07-23T18:28:40.053

If it is important that you have two different lists, and those lists are both in the same order (first element of party member list corresponds with first element of hp list) then you can zip the two lists and iterate over them both simultaneously.

If you want to modify the elements of the list, however, then you can enumerate them, allowing you to keep track of the index as you loop over the two lists, and then modify the lists by index in the loop.

for i, (member, hp) in enumerate(zip(members, hitpoints)):
    print(member, hp)
    if member == 'Bob':
        hitpoints[i] -= 10

However, I would recommend making a dict, a different data structure than using two lists, but much more elegant to use.

>>> members = ['A', 'B', 'C']
>>> hp = [5, 10, 7]
>>> member_hp = dict(zip(members, hp))

>>> member_hp['A']
5
>>> member_hp['A'] -= 3
>>> member_hp['A']
2
>>> member_hp['D'] = 20 # adds new member D with hp of 20

For slightly (and I mean only very slightly) more advanced usage, you can use the json module to read and write this data to a text file, to persist across multiple sessions.

Is there a way to modify hp corresponding with a party member? For example, could I have a function that said Damage(member,dmg) that took away dmg amount of points from member's hp? — The .Anonymoose, Jul 23 '18 at 17:55
Since keeping it simple seems best for your purposes, I updated the logic to demonstrate how you would modify the hp based on a name in members. I would recommend learning a little more about object oriented programming or using python dicts (read about JSON, they are essentially the same thing, and can easily be stored in a text file) to increase the flexibility of your design, however. — swhat, Jul 23 '18 at 18:04

score 0 · Answer 2 · answered Jul 23 '18 at 17:45

I would use a combination of both recommendations in the comments section. Using OOP seems to be optimal here, so, below is a short possible example

class Party(dict):
  def add_member(self,member):
    self[member.name] = member.hp

  def party_hp(self):
    total_hp = 0
    for name,hp in self.items():
      total_hp += hp
    return total_hp

class Member():
  def __init__(self, name, hp):
    self.name = name
    self.hp = hp

player1 = Member("player1",10)
player2 = Member("player2",10)
player3 = Member("player3",10)
player4 = Member("player4",10)

test_party = Party()
test_party.add_member(player1)
test_party.add_member(player2)
test_party.add_member(player3)
test_party.add_member(player4)

print(test_party.party_hp())
>>>> 40

Note that this is just to show how OOP can be a real viable solution. Basically, in my example you have a Party class that hold a dictionary of members. Calling party_hp on it will return you the total hp of the party.

The exact implementation can be totally different. You could for example accept a list of users to shorten the number of code lines needed when adding members to a Party. Again, this is a skeleton of what you could use.

Thank you for your suggestion. Unfortunately, I haven't learned about classes yet, but I will definitely look back on this when I do. — The .Anonymoose, Jul 23 '18 at 17:53

Is there a way to pull corresponding items from different lists in python?

2 Answers2