Develop Reference

Function vs if-statement: Function is not working, but the code in the function will work when outside a function?

I was working on building a randomized character generator for Pathfinder 3.5 and got stuck.
I am using the Populate_Skills(Skill_String, Draw, Skill_List, Class_Skill): function to populate a randiomized list of skills with their class based points total, class bonus, and point buy. So modelling the action of a player picking skills for their character.
As an example below, Wizards.
I pick Knowledge_Arcana as a skill and spend one of my skill point pool (Calculated by taking my intelligence modifier +2) on it. So that skill now equals my intelligence modifier(+1 in this case), class skill bonus as a wizard (+3), plus the point I spent(+1) for a total of 5.
The problem is while the function prints the correct result of 5, the outstanding variables do not populate with the final total. To continue our example I'd run the function on Knowledge_Arcana, get a +5, and then check the Knowledge_Arcana after the function call and get just +1. Conversely, if I write out the function as just an if statement it works. Example is next to the function for comparison.
Does anyone know why Im getting the different result?
## Creating the lists and breaking into two separate sections
Int_Mod = 1
Skill_Ranks = 3
Rand_Class = 'Wizard'
Knowledge_Arcana = Int_Mod
Knowledge_Dungeoneering = Int_Mod
Wizard_Class_Top_Skills = ["Knowledge_Arcana"]
Wizard_Class_Less_Skills = ["Knowledge_Dungeoneering"]
Class_Skill = 3
Important_Skills_Weighted = .6
Less_Important_Skills_Weighted = .4
Important_Skills_Total_Weighted = round(Skill_Ranks*Important_Skills_Weighted)
Less_Skill_Total_Weighted = round(Skill_Ranks*Less_Important_Skills_Weighted)
Wiz_Draw =['Knowledge_Arcana', 'Knowledge_Dungeoneering']
def Populate_Skills(Skill_String, Draw, Skill_List, Class_Skill):
if Skill_String in Draw:
Skill_List = Skill_List + Class_Skill + Draw.count(Skill_String)
print(Skill_String, Skill_List)
else:
print('Nuts!')
## Function Calls
Populate_Skills('Knowledge_Arcana', Wiz_Draw, Knowledge_Arcana, Class_Skill)
Populate_Skills('Knowledge_Dungeoneering', Wiz_Draw, Knowledge_Dungeoneering, Class_Skill)
print(Knowledge_Arcana,Knowledge_Dungeoneering)
Edited to be a MRE, I believe. Sorry folks, Im new.

You are passing in a reference to a list and expect the function to modify it; but you are reassigning the variable inside the function which creates a local variable, which is then lost when the function is exited. You want to manipulate the same variable which the caller passed in, instead.
def Populate_Skills(Skill_String, Draw, Skill_List, Class_Skill):
if Skill_String in Draw:
Skill_List.extend(Class_Skill + Draw.count(Skill_String))
print(Skill_String, Skill_List)
else:
print('Nuts!')
Alternatively, have the function return the new value, and mandate for the caller to pick it up and assign it to the variable.
def Populate_Skills(Skill_String, Draw, Skill_List, Class_Skill):
if Skill_String in Draw:
Skill_List = Skill_List + Class_Skill + Draw.count(Skill_String)
print(Skill_String, Skill_List)
else:
print('Nuts!')
return Skill_List
Skill_List = Populate_Skills('Knowledge_Arcana', Wiz_Draw, Knowledge_Arcana, Class_Skill)
# etc
You should probably also rename your variables (capital letters should be used for classes and globals; regular Python functions and variables should use snake_case) and avoid using global variables at all. The entire program looks like you should probably look into refactoring it into objects, but that's far beyond the scope of what you are asking.

How to get rid of the global variables

I don't want to use the global-variable, but how do I make this without them?
(I have more functions and so on, so this isn't all)
Players turn. I use the global-variable to make sure the turns are switching, tried some other sulotion however the turns didn't switch...
#Check if the shot hit any computerships
def player_hit_check():
global players_turn
shot = player_shot()
check_if_hit = set(computer_ships) & set(player_turn_shot)
if(check_if_hit == set()):
print("You missed! Switching turns...")
time.sleep(3)
players_turn = 1
else:
print(f"YOU MADE A BIG BANG ON ",player_turn_shot,"!")
computer_ships.remove(shot)
all_player_hits.append(shot)
Computers turn
#Check if the computers shot hit any player ships
def computer_hit_check():
global computers_turn
computer_random_shot = computer_shot()
check_if_hit = set(player_ships) & set(computer_turn_shot)
if(check_if_hit == set()):
print("Computer missed! It's now your turn.")
time.sleep(3)
computers_turn = 1
else:
print(f"COMPUTER MADE A BIG BANG ON ",computer_turn_shot,"!")
player_ships.remove(computer_random_shot)
all_computer_hits.append(computer_random_shot)
The game it self
#Runs the game
while True:
#Players turn
players_turn = 0
while players_turn < 1:
print('\n'.join('\t'.join(row) for row in board.values()))
print("Playerships:",player_ships)
print("Computerships:",computer_ships)
print("You have shot on",all_player_shots,"and has knocked out these ships:",all_player_hits)
print("The computer has shot at these coordinates",all_computer_shots,"and has knocked out these ships:",all_computer_hits)
player_hit_check()
#Computers turn
computers_turn = 0
while computers_turn < 1:
computer_hit_check()

In your case you don't need global variables at all. Your program is not using them to carry information back and forth.
In your case you just need to get information back from your functions. So in the case of player_hit_check():
def player_hit_check():
shot = player_shot()
check_if_hit = set(computer_ships) & set(player_turn_shot)
if(check_if_hit == set()):
print("You missed! Switching turns...")
time.sleep(3)
return 1
else:
print(f"YOU MADE A BIG BANG ON ",player_turn_shot,"!")
computer_ships.remove(shot)
all_player_hits.append(shot)
return 0
And the call site would be like this:
while True:
#Players turn
players_turn = 0
while players_turn < 1:
# prints elided ...
players_turn = player_hit_check()

The problem with global variables is, that they fly around in an unstructured manner.
There are several approaches to solve global variables
One first step to get rid of global variables is to use singletons (https://en.wikipedia.org/wiki/Singleton_pattern). This will bundle similar values into one class. So the values are more structured and easier to track.
Use classes. If the global value is used in an environment that can be associated to a single responsibility, it can be productive to bundle all functions in a class and make the global variable to a class variable or property of the class
Pass it through. In many programs there is the need of settings class or state class. Put everything in there that defines the current state or starting state of the program and pass it through your code. The downside of passing is, that this classes tend to become almighty classes that appear in every constructor.
There are certainly more approaches how to get rid of global variables, but this are some common strategies.

How to match input with elements in list/dictionary in Python3

I'm very new at coding, and I'm trying to create a shop list with items and prices on it.
That is, once typed in all the items, the function should calculate the sum and stop the moment you exceed the budget.
So I wrote something like:
def shoplist():
list={"apple":30, "orange":20, "milk":60......}
buy=str(input("What do you want to purchase?")
If buy in list:
While sum<=budget:
sum=sum+??
shoplist ()
I really don't know how to match the input of an item with the price in the list...
My first thought is to use 'if', but it's kinda impractical when you have more than 10 items on the list and random inputs.
I'm in desperate need of help....So any suggestions would be nice!! (or if you have a better solution and think me writing it this way is complete garbage... PLEASE let me know what those better solutions are😭😭😭

The code you post will not run in python. list is a builtin and should not be used for a variable name, and is doubly confusing since it refers to a dict object here. input() already returns a str so the cast has no effect. if and while should be lowercase, and there is no indentation, so we have no way of knowing the limits of those statements.
There are so many things wrong, take a look at this:
def shoplist(budget):
prices = {"apple":30, "orange":20, "milk":60}
# Initialise sum
sum = 0
while sum <= budget:
buy = input("What do you want to purchase?")
# Break out of the loop if the user hts <RETURN>
if not buy: break
if buy in prices:
sum += prices[buy] # This gets the price
else:
print("Invalid item", buy)
shoplist(142)
So what have I changed? The budget has to come from somewhere, so I pass it in as a parameter (142, I made that up). I initialise the sum to zero, and I moved the while loop to the outside.
Notice as well lots of whitespace - it makes the code easier to read and has no effect on performance.
Lots of improvements to make. The user should be shown a list of possible items and prices and also how much budget there is left for each purchase. Note as well that it is possible to go over budget since we might only have 30 in the budget but we can still buy milk (which is 60) - we need another check (if statement) in there!
I'll leave the improvements to you. Have fun!

Take a look at this as an example:
# this is a dictionary not a list
# be careful not using python reserved names as variable names
groceries = {
"apple":30,
"orange":20,
"milk":60
}
expenses = 0
budget = 100
cart = []
# while statements, as well as if statements are in lower letter
while expenses < budget:
# input always returns str, no need to cast
user_input = input("What do you want to purchase?")
if user_input not in groceries.keys():
print(f'{user_input} is not available!')
continue
if groceries[user_input] > budget - expenses:
print('You do not have enough budget to buy this')
user_input = input("Are you done shopping?Type 'y' if you are.")
if user_input == 'y':
break
continue
cart.append(user_input)
# this is how you add a number to anotherone
expenses += groceries[user_input]
print("Shopping cart full. You bought {} items and have {} left in your budget.".format(len(cart), budget-expenses))

I've made some changes to your code to make it work, with explanation including using comments indicated by the # symbol.
The two most important things are that all parentheses need to be closed:
fun((x, y) # broken
fun((x, y)) # not broken
and keywords in Python are all lowercase:
if, while, for, not # will work
If, While, For, Not # won't work
You might be confused by True and False, which probably should be lowercase. They've been that way so long that it's too late to change them now.
budget = 100 # You need to initialize variables before using them.
def shoplist():
prices = { # I re-named the price list from list to prices
'apple' : 30, # because list is a reserved keyword. You should only
'orange' : 20, # use the list keyword to initialize list objects.
'milk' : 60, # This type of object is called a dictionary.
} # The dots .... would have caused an error.
# In most programming languages, you need to close all braces ().
# I've renamed buy to item to make it clearer what that variable represents.
item = input('What do you want to purchase? ')
# Also, you don't need to cast the value of input to str;
# it's already a str.
if item in prices:
# If you need an int, you do have to cast from string to int.
count = int(input('How many? '))
cost = count*prices[item] # Access dictionary items using [].
if cost > budget:
print('You can\'t afford that many!')
else:
# You can put data into strings using the % symbol like so:
print('That\'ll be %i.' % cost) # Here %i indicates an int.
else:
print('We don\'t have %s in stock.' % item) # Here %s means str.
shoplist()
A lot of beginners post broken code on StackOverflow without saying that they're getting errors or what those errors are. It's always helpful to post the error messages. Let me know if you have more questions.

Defining global variables to hold values that will be referenced by a raw_input

I am making a text based RPG. With that bit of context, let's say I wanted to make a global list of spells, and then define certain actions for those spells to take when called upon by a user. So if I have a global list of spells, what is the best way to assign certain actions for those spells to have? This is a bit of code that will help you somewhat understand my combat mechanics. I need to allow the user to call upon 'heal', for example, and then have heal hold the properties of raising health numbers and a cool down mechanic, e.g. "You must wait 5s to use this spell again." What's the best way to define those properties, and have those properties be global, so they can be referenced through each combat function without having to reiterate the properties?
Here is a portion of my code that may clear up my combat mechanics. When the player is prompted under raw_input 'inp' to type the name of the spell, and they type heal, a cool down effect should apply for a certain length of time, or perhaps a certain number of turns in combat, as well as the ability to raise user life. The property I use for life is under a class called 'user' and a variable 'health'. So user.health = 100 is valid
available_spells = ['heal', 'fireball']
equipped = {'Armor': 'Mage Robes',
'Weapon': 'Wooden Staff',
'Spells': ['heal', 'fireball']
print "Your available spell(s) is(are) '%s'. " % equipped["Spells"]
inp = raw_input("Type the name of a spell you want to use.: ").lower()
lst = [x for x in available_spells if x.startswith(inp)]
if len(lst) == 0:
print "No such spell"
print ' '
elif len(lst) == 1:
spell = lst[0]
print "You picked", spell
#combat functions here
else:
print "Which spell of", equipped["Spells"], "do you mean?"

Answer Error, Only outputting Zero

I am coding in python and I cannot seem to figure out why when the amount of tickets sold is entered it does not calculate the full price of the tickets that were sold. Any help is appreciated, Thanks.
aLimit=300
bLimit=500
cLimit=100
aPrice=20
bPrice=15
cPrice=10
ticketSold=1
totalIncome=0
def Main():
getTickets(aLimit)
sectionIncome=calcIncome(ticketSold,aPrice)
sectionIncome+=totalIncome
print("The theater generated this much money from section A "+
str(sectionIncome))
getTickets(bLimit)
sectionIncome=calcIncome(ticketSold,bPrice)
sectionIncome+=totalIncome
print("The theater generated this much money from section B "+
str(sectionIncome))
getTickets(cLimit)
sectionIncome=calcIncome(ticketSold,cPrice)
sectionIncome+=totalIncome
print("The theater generated this much money from section C "+
str(sectionIncome))
print("The Theater generated "+str(totalIncome)+" total in ticket sales.")
def getTickets(limit):
ticketSold=int(input("How many tickets were sold? "))
if (ticketsValid(ticketSold,limit)==True):
return ticketSold
else:
getTickets(limit)
def ticketsValid(Sold,limit):
while (Sold>limit or Sold<0):
print("ERROR: There must be tickets less than "+
str(limit)+" and more than 0")
return False
return True
def calcIncome(ticketSold,price):
return ticketSold*price
Main()

How to debug your (small) program
Okay so let's start from the top and go line-by-line. There's a lot of issues here.
aLimit=300
bLimit=500
cLimit=100
aPrice=20
bPrice=15
cPrice=10
ticketSold=1
totalIncome=0
These are all globals since you defined them in the module scope. That's a Bad Thing. Don't do it. If they're constants, use CAPS to mention that, but they should still not be global.
def Main(): # I mentioned in my comment, but Capitals are classes
# by convention, use def main() instead
getTickets(aLimit)
Let's stop and look at getTickets() so we can follow execution
def getTickets(limit): # camelCase is not advised per PEP8, but it's still around
# so I wouldn't worry about this one so much as Capitalized
ticketSold=int(input("How many tickets were sold? "))
# perfect implementation, though be prepared for users who
# will type forty instead of 40!
if (ticketsValid(ticketSold,limit)==True):
return ticketSold
# so any time you write `if ___ == True`, stop and realize that the compare
# is unnecessary. if ticketsValid(ticketSold,limit) works just as well!
else:
getTickets(limit)
# wha-? If the tickets aren't valid, we're RECURSING??! This is an infinite loop.
# are you doing this to prompt for more input if tickets aren't valid? That's Bad
Okay so you invoked ticketsValid in there, so let's look there now...
def ticketsValid(Sold,limit): # another Capital here!
while Sold > limit or Sold < 0: # this should be an if??
print ("...")
return False
return True
# Since you have a set amount, this is MUCH easier written as:
## def ticketsValid(sold,limit):
## return 0 < sold < limit
# but should this be <=?
Alright, back to main--ahem--Main....
def Main():
...
sectionIncome = calcIncome(ticketSold,aPrice)
And hop back to calcIncome
def calcIncome(ticketSold,price):
return ticketSold*price # why not just substitute this???
Main again
def Main():
...
sectionIncome += totalIncome
# this sets sectionIncome equal to the current value of sectionIncome
# plus the current value of totalIncome, which is currently zero.
Then basically the whole thing gets repeated down the function. There's your issue, the += adds zero to sectionIncome instead of adding sectionIncome to totalIncome!
The better way to do this!
Here's the problem. You're trying to use functional programming to do object-oriented tasks. Most of these kind of issues are when new programmers who are interested in video games think that the best task to learn programming is a text adventure. Unfortunately, the best languages for text adventures (those that easily implement a Finite State Machine) are not usually those that beginners start with, so it's hard to implement WELL!
In your case, you should be creating objects to do the workload for you. Python does this elegantly, but it's rarely in beginning tutorials. As an example, I wrote out a bit that does exactly what you did (defines three sections of seating in a theater and sells one ticket per section)
class Section(object):
def __init__(self,price,limit):
self.price = price
self.tickets_sold = 0
self.limit = limit
#property
def sales(self):
return self.price*self.tickets_sold
def sell(self,qty=1):
if not isinstance(qty,int): raise TypeError("Must sell an int of tickets")
if qty < 1: raise ValueError("Must sell positive tickets")
qty = min(qty,self.limit-self.tickets_sold)
self.tickets_sold += qty
# optional print statement for the user
class Theater(object):
def __init__(self,sections):
self.sections = sections
#property
def sales(self):
return sum(section.sales for section in self.sections)
theater = Theater([Section(20,300),
Section(15,500),
Section(10,100)])
for section in theater.sections:
section.sell(1)
print(theater.sales)
The big problem with this is just that you don't know how to do it. Creating an object that will stay constant, then throw several instances of it around with specific attributes is precisely the approach I would favor in this circumstance.

read up on the += operator. totalIncome is only ever set to 0.

You need to replace sectionIncome+=totalIncome with totalIncome+=sectionIncome
Code
aLimit=300
bLimit=500
cLimit=100
aPrice=20
bPrice=15
cPrice=10
ticketSold=1
totalIncome=0
def Main():
getTickets(aLimit)
sectionIncome=calcIncome(ticketSold,aPrice)
totalIncome=sectionIncome
print("The theater generated this much money from section A "+str(sectionIncome))
getTickets(bLimit)
sectionIncome=calcIncome(ticketSold,bPrice)
totalIncome+=sectionIncome
print("The theater generated this much money from section B "+str(sectionIncome))
getTickets(cLimit)
sectionIncome=calcIncome(ticketSold,cPrice)
totalIncome+=sectionIncome
print("The theater generated this much money from section C "+str(sectionIncome))
print("The Theater generated "+str(totalIncome)+" total in ticket sales.")
def getTickets(limit):
ticketSold=int(input("How many tickets were sold? "))
if (ticketsValid(ticketSold,limit)==True):
return ticketSold
else:
getTickets(limit)
def ticketsValid(Sold,limit):
while (Sold>limit or Sold<0):
print ("ERROR: There must be tickets less than "+str(limit)+" and more than 0")
return False
return True
def calcIncome(ticketSold,price):
return ticketSold*price
Main()

sectionIncome+=totalIncome
This is the wrong way around. To add to totalIncome the value of sectionIncome, the syntax is
totalIncome+=sectionIncome
You will allso need to add global totalIncome to the beginning of Main -- or, better yet, do away with the global variables completely, like you have often been told before.
Finally, your getTickets function returns a calculated value, but the code which calls it doesn't store that result anywhere. Instead, you simply set ticketSold=1 in the global initialization, then use that as the multiplier instead of the actual number of tickets input by the user.
As a general observation, you have a lot of repetitive code, while the functions you do have are not very useful (they do not encapsulate complex behavior, nor repeated functionality). If you are a beginner, concentrate on a straightforward flow, then factor out complex repeating operations to loops or functions. Perhaps something like this:
def income ():
total = 0
for ticket_type, limit, price in [('A', 300, 20),
('B', 500, 15),
('C', 100, 10)]:
print "How many %s tickets sold? (Max %d):" % (ticket_type, limit),
sold = -1
while sold < 0 or sold > limit:
if sold != -1:
print "Sorry. Try again:",
sold = raw_input()
try:
sold = int(sold)
except:
pass
total += sold*price
print "total %d" % total
income()
Please also note the user-friendly gesture of indicating the maximum allowed for each category in the input prompt (-:
The loop driver is a bit of a wart; a slicker way to do that would be to declare a class TicketCategory and have three instances A, B, and C with methods to report back their name, price, and available amounts, but that's for later.