I am trying to make a datalogging code, for the user to input the number and age of animals, the birth rate and their chances of surviving the generation. I have tried to use return but when I run the program, the variables remain at 0.
Here I have initiated the variables
Gen0_J=0
Gen0_A=0
Gen0_S=0
Birth_rate=0
Srate_J=0
Srate_A=0
Srate_S=0
New_generations=5
My first function
def generation_values():
Gen0_J=int(input("How many juveniles in Generation 0? "))
Gen0_A=int(input("How many adults in Generation 0? "))
Gen0_S=int(input("How many seniles in Generation 0? "))
Srate_J=float(input("What is the survival rate for juveniles? "))
Srate_A=float(input("What is the survival rate for adults? "))
Srate_S=float(input("What is the survival rate for seniles? "))
Birth_rate=int(input("What is the birth rate? "))
return Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate
displaying the variables
def display_values():
print("\nThe amount of juveniles in Generation 0 is",Gen0_J)
print("The amount of adults in Generation 0 is",Gen0_A)
print("The amount of seniles in Generation 0 is",Gen0_S)
print("The birth rate in Generation 0 is",Birth_rate)
print("The survival rate for juveniles in Generation 0 is",Srate_J)
print("The survival rate for adults in Generation 0 is",Srate_A)
print("The survival rate for seniles in Generation 0 is",Srate_S)
generation_values()
display_values()
However, the variables stay at 0
How many juveniles in Generation 0? 5
How many adults in Generation 0? 6
How many seniles in Generation 0? 7
What is the survival rate for juveniles? 0.75
What is the survival rate for adults? 1
What is the survival rate for seniles? 0
What is the birth rate? 2
The amount of juveniles in Generation 0 is 0
The amount of adults in Generation 0 is 0
The amount of seniles in Generation 0 is 0
The birth rate in Generation 0 is 0
The survival rate for juveniles in Generation 0 is 0
The survival rate for adults in Generation 0 is 0
The survival rate for seniles in Generation 0 is 0
The scope of your variables is incorrect. [variables declared inside a function, inside a class, or inside a module are not accessible at a higher level in your program - here is a short description of python scoping rules that super_biased_man posted in the comments]- in this case, the variables you are assigning to in generation_values()
are defined locally.
It is surely not the proper way to do this, but declaring the variables global in generation_values()
will solve your problem: (defining what would be an "ideal way" of doing this is dependent on where you are at in your study of programming & would take us too far)
Gen0_J=0
Gen0_A=0
Gen0_S=0
Birth_rate=0
Srate_J=0
Srate_A=0
Srate_S=0
New_generations=5
def generation_values():
global Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate
Gen0_J=int(input("How many juveniles in Generation 0? "))
Gen0_A=int(input("How many adults in Generation 0? "))
Gen0_S=int(input("How many seniles in Generation 0? "))
Srate_J=float(input("What is the survival rate for juveniles? "))
Srate_A=float(input("What is the survival rate for adults? "))
Srate_S=float(input("What is the survival rate for seniles? "))
Birth_rate=int(input("What is the birth rate? "))
return Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate
def display_values():
print("\nThe amount of juveniles in Generation 0 is",Gen0_J)
print("The amount of adults in Generation 0 is",Gen0_A)
print("The amount of seniles in Generation 0 is",Gen0_S)
print("The birth rate in Generation 0 is",Birth_rate)
print("The survival rate for juveniles in Generation 0 is",Srate_J)
print("The survival rate for adults in Generation 0 is",Srate_A)
print("The survival rate for seniles in Generation 0 is",Srate_S)
generation_values()
display_values()
An alternate way of handling this would be to pass the variables as arguments to your functions, and return them with values assigned... But there are a lot of them and passing them around is maybe going to clutter your code.
You could also gather them in a tuple or wrap them in a class.
The scope of your variables is not consistent.
You could do it this way:
def generation_values():
Gen0_J=int(input("How many juveniles in Generation 0? "))
Gen0_A=int(input("How many adults in Generation 0? "))
Gen0_S=int(input("How many seniles in Generation 0? "))
Srate_J=float(input("What is the survival rate for juveniles? "))
Srate_A=float(input("What is the survival rate for adults? "))
Srate_S=float(input("What is the survival rate for seniles? "))
Birth_rate=int(input("What is the birth rate? "))
return Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate
def display_values(Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate):
print("\nThe amount of juveniles in Generation 0 is",Gen0_J)
print("The amount of adults in Generation 0 is",Gen0_A)
print("The amount of seniles in Generation 0 is",Gen0_S)
print("The birth rate in Generation 0 is",Birth_rate)
print("The survival rate for juveniles in Generation 0 is",Srate_J)
print("The survival rate for adults in Generation 0 is",Srate_A)
print("The survival rate for seniles in Generation 0 is",Srate_S)
Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate = generation_values()
display_values(Gen0_J,Gen0_A,Gen0_S,Srate_J,Srate_A,Srate_S,Birth_rate)
would be a first step.
This way, the variables in the "main" namespace is separated from the variables in the functions.
A next step to remove repetition could be not to care about the separation of the variables in the main namespace, just to treat them as a tuple:
data = generation_values()
display_values(*data)
Further steps to remove repetition and to intoduce clarity could include:
As others have stated, the problem is that assignments to variables inside of a function create new variables instead of assigning the values to the globals. This is why the global
keyword exists.
In this case, I would consider using a class since you have a number of related state values that you manipulate together.
class GenerationData(object):
def __init__(self, gen_number):
self.number = gen_number
self.birth_rate = 0
self.num_juveniles, self.num_adults, self.num_seniles = 0, 0, 0
self.juvenile_rate, self.adult_rate, self.senile_rate = 0.0, 0.0, 0.0
@classmethod
def read(cls, gen_number):
gen = cls(gen_number)
gen.num_juveniles = read_integer(
'How many juveniles in Generation {}?'.format(gen_number))
gen.num_adults = read_integer(
'How many adults in Generation {}?'.format(gen_number))
gen.num_seniles = read_integer(
'How many seniles in Generation {}?'.format(gen_number))
gen.juvenile_rate = read_float(
'What is the survival rate for juveniles? ')
gen.adult_rate = read_float('What is the survival rate for adults? ')
gen.senile_rate = read_float('What is the survival rate for seniles? ')
gen.birth_rate = read_integer('What is the birth rate? ')
def display(self):
print('The amount of juveniles in Generation', self.number,
'is', self.num_juveniles)
print('The amount of adults in Generation', self.number,
'is', self.num_adults)
print('The amount of seniles in Generation', self.number,
'is', self.num_seniles)
print('The birth rate in Generation', self.number,
'is', self.birth_rate)
print('The survival rate for juveniles in Generation', self.number,
'is', self.juvenile_rate)
print('The survival rate for adults in Generation', self.number,
'is', self.adult_rate)
print('The survival rate for seniles in Generation', self.number,
'is', self.senile_rate)
def read_integer(prompt):
return int(raw_input(prompt))
def read_float(prompt):
return float(raw_input(prompt))
first_generation = Generation.read(0)
first_generation.display()
This will make things easier when you are manipulating the generation data since it is all bundled into a single object.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.