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Mutable named tuple with default value and conditional rounding support

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6

1

$begingroup$

I have following code to create a mutable namedtuple. based my understand I can use dataclass to do it. is there a better way to do it or clean up the code?

@dataclass
class Price:
 """
 This describes how to map default price value for product
 """
 profit: float = 0.5
 cost: float = 0.1
 sale: float = 25.0

 def round(self, n: float):
 if n < 1:
 return round(n, 2)
 elif n < 100:
 n = round(n / 1)
 elif n < 1000:
 n = round(n / 5) * 5
 elif n < 10000:
 n = round(n / 50) * 50
 else:
 n = round(n / 500) * 500
 return n

 def update(self, **kwargs):
 rate = kwargs.get('rate', 1)
 for k, v in asdict(self).items():
 if k != 'sale':
 v = self.round(v * rate)
 v = kwargs.get(k) or v
 setattr(self, k, float(v))

#run test
p = Price()
p.update(rate=1) #p = Price(profit=0.5, cost=0.1, sale=25.0)

p = Price()
p.update(**sale=450, **dict(rate=0.9073)) #p = Price(profit=0.45, cost=0.1, sale=450.0)

p = Price()
p.update(**sale=800, **dict(rate=301.377)) #p = Price(profit=150.0, cost=0.1, sale=800.0)

p = Price()
p.update(rate=301.377) #p = Price(profit=150.0, cost=0.1, sale=7550.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=1) #p = Price(profit=0.0, cost=0.5, sale=50.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=600, **dict(rate=0.9073)) #p = Price(profit=0.0, cost=0.5, sale=600.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=1200, **dict(rate=301.377)) #p = Price(profit=0.0, cost=0.5, sale=1200.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=301.377) #p = Price(profit=0.0, cost=0.5, sale=15000.0)

python python-3.x

share|improve this question

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Any particular reason you're not using python's built-in round function or Decimal class?
  $endgroup$
  – scnerd
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  It's fairly clear what you mean by this question, although there are some terminology issues. Tuples by definition are immutable.
  $endgroup$
  – Reinderien
  3 hours ago
  

  
  
  
  

add a comment
 | 

6

1

$begingroup$

I have following code to create a mutable namedtuple. based my understand I can use dataclass to do it. is there a better way to do it or clean up the code?

@dataclass
class Price:
 """
 This describes how to map default price value for product
 """
 profit: float = 0.5
 cost: float = 0.1
 sale: float = 25.0

 def round(self, n: float):
 if n < 1:
 return round(n, 2)
 elif n < 100:
 n = round(n / 1)
 elif n < 1000:
 n = round(n / 5) * 5
 elif n < 10000:
 n = round(n / 50) * 50
 else:
 n = round(n / 500) * 500
 return n

 def update(self, **kwargs):
 rate = kwargs.get('rate', 1)
 for k, v in asdict(self).items():
 if k != 'sale':
 v = self.round(v * rate)
 v = kwargs.get(k) or v
 setattr(self, k, float(v))

#run test
p = Price()
p.update(rate=1) #p = Price(profit=0.5, cost=0.1, sale=25.0)

p = Price()
p.update(**sale=450, **dict(rate=0.9073)) #p = Price(profit=0.45, cost=0.1, sale=450.0)

p = Price()
p.update(**sale=800, **dict(rate=301.377)) #p = Price(profit=150.0, cost=0.1, sale=800.0)

p = Price()
p.update(rate=301.377) #p = Price(profit=150.0, cost=0.1, sale=7550.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=1) #p = Price(profit=0.0, cost=0.5, sale=50.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=600, **dict(rate=0.9073)) #p = Price(profit=0.0, cost=0.5, sale=600.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=1200, **dict(rate=301.377)) #p = Price(profit=0.0, cost=0.5, sale=1200.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=301.377) #p = Price(profit=0.0, cost=0.5, sale=15000.0)

python python-3.x

share|improve this question

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Any particular reason you're not using python's built-in round function or Decimal class?
  $endgroup$
  – scnerd
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  It's fairly clear what you mean by this question, although there are some terminology issues. Tuples by definition are immutable.
  $endgroup$
  – Reinderien
  3 hours ago
  

  
  
  
  

add a comment
 | 

$begingroup$

I have following code to create a mutable namedtuple. based my understand I can use dataclass to do it. is there a better way to do it or clean up the code?

@dataclass
class Price:
 """
 This describes how to map default price value for product
 """
 profit: float = 0.5
 cost: float = 0.1
 sale: float = 25.0

 def round(self, n: float):
 if n < 1:
 return round(n, 2)
 elif n < 100:
 n = round(n / 1)
 elif n < 1000:
 n = round(n / 5) * 5
 elif n < 10000:
 n = round(n / 50) * 50
 else:
 n = round(n / 500) * 500
 return n

 def update(self, **kwargs):
 rate = kwargs.get('rate', 1)
 for k, v in asdict(self).items():
 if k != 'sale':
 v = self.round(v * rate)
 v = kwargs.get(k) or v
 setattr(self, k, float(v))

#run test
p = Price()
p.update(rate=1) #p = Price(profit=0.5, cost=0.1, sale=25.0)

p = Price()
p.update(**sale=450, **dict(rate=0.9073)) #p = Price(profit=0.45, cost=0.1, sale=450.0)

p = Price()
p.update(**sale=800, **dict(rate=301.377)) #p = Price(profit=150.0, cost=0.1, sale=800.0)

p = Price()
p.update(rate=301.377) #p = Price(profit=150.0, cost=0.1, sale=7550.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=1) #p = Price(profit=0.0, cost=0.5, sale=50.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=600, **dict(rate=0.9073)) #p = Price(profit=0.0, cost=0.5, sale=600.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=1200, **dict(rate=301.377)) #p = Price(profit=0.0, cost=0.5, sale=1200.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=301.377) #p = Price(profit=0.0, cost=0.5, sale=15000.0)

python python-3.x

share|improve this question

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

$endgroup$

@dataclass
class Price:
 """
 This describes how to map default price value for product
 """
 profit: float = 0.5
 cost: float = 0.1
 sale: float = 25.0

 def round(self, n: float):
 if n < 1:
 return round(n, 2)
 elif n < 100:
 n = round(n / 1)
 elif n < 1000:
 n = round(n / 5) * 5
 elif n < 10000:
 n = round(n / 50) * 50
 else:
 n = round(n / 500) * 500
 return n

 def update(self, **kwargs):
 rate = kwargs.get('rate', 1)
 for k, v in asdict(self).items():
 if k != 'sale':
 v = self.round(v * rate)
 v = kwargs.get(k) or v
 setattr(self, k, float(v))

#run test
p = Price()
p.update(rate=1) #p = Price(profit=0.5, cost=0.1, sale=25.0)

p = Price()
p.update(**sale=450, **dict(rate=0.9073)) #p = Price(profit=0.45, cost=0.1, sale=450.0)

p = Price()
p.update(**sale=800, **dict(rate=301.377)) #p = Price(profit=150.0, cost=0.1, sale=800.0)

p = Price()
p.update(rate=301.377) #p = Price(profit=150.0, cost=0.1, sale=7550.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=1) #p = Price(profit=0.0, cost=0.5, sale=50.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=600, **dict(rate=0.9073)) #p = Price(profit=0.0, cost=0.5, sale=600.0)

p = Price(0.0, 0.5, 50.0)
p.update(**sale=1200, **dict(rate=301.377)) #p = Price(profit=0.0, cost=0.5, sale=1200.0)

p = Price(0.0, 0.5, 50.0)
p.update(rate=301.377) #p = Price(profit=0.0, cost=0.5, sale=15000.0)

share|improve this question

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

share|improve this question

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

edited 5 hours ago

200_success

136k2121 gold badges175175 silver badges445445 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

asked 9 hours ago

jacobcan118jacobcan118

18666 bronze badges

1 Answer
1

active

oldest

votes

7

$begingroup$

In short:

• dataclass is the right thing to use as a mutable named tuple. It's basically custom-built to be a great version of that idea.




• Use decimal.Decimal for any financial numbers.




• Don't re-implement round. There's a built-in version that behaves in nice, configurable ways with the Decimal object.




• Not sure what the p.update(**sale=600, **dict(rate=0.9073)) is all about, just use p.update(sale=600, rate=0.9073) (except with Decimals)

share|improve this answer

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  what should I use build-in round version ? based on the logic of round I have?
  $endgroup$
  – jacobcan118
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Because the builtin version does all yours does, and is tested against all manner of edge cases that yours is not. And if it ever becomes important, it's also faster. So you can just remove the method.
  $endgroup$
  – Gloweye
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  so how can i use to round in the same logic? 102 -> round to 100, 103 -> round to 5 , 1023 -> 1000, 1044 -> 1050
  $endgroup$
  – jacobcan118
  4 hours ago
  

  
  
  
  

add a comment
 | 

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7

$begingroup$

In short:

• dataclass is the right thing to use as a mutable named tuple. It's basically custom-built to be a great version of that idea.




• Use decimal.Decimal for any financial numbers.




• Don't re-implement round. There's a built-in version that behaves in nice, configurable ways with the Decimal object.




• Not sure what the p.update(**sale=600, **dict(rate=0.9073)) is all about, just use p.update(sale=600, rate=0.9073) (except with Decimals)

share|improve this answer

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  what should I use build-in round version ? based on the logic of round I have?
  $endgroup$
  – jacobcan118
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Because the builtin version does all yours does, and is tested against all manner of edge cases that yours is not. And if it ever becomes important, it's also faster. So you can just remove the method.
  $endgroup$
  – Gloweye
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  so how can i use to round in the same logic? 102 -> round to 100, 103 -> round to 5 , 1023 -> 1000, 1044 -> 1050
  $endgroup$
  – jacobcan118
  4 hours ago
  

  
  
  
  

add a comment
 | 

7

$begingroup$

In short:

• dataclass is the right thing to use as a mutable named tuple. It's basically custom-built to be a great version of that idea.




• Use decimal.Decimal for any financial numbers.




• Don't re-implement round. There's a built-in version that behaves in nice, configurable ways with the Decimal object.




• Not sure what the p.update(**sale=600, **dict(rate=0.9073)) is all about, just use p.update(sale=600, rate=0.9073) (except with Decimals)

share|improve this answer

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  what should I use build-in round version ? based on the logic of round I have?
  $endgroup$
  – jacobcan118
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Because the builtin version does all yours does, and is tested against all manner of edge cases that yours is not. And if it ever becomes important, it's also faster. So you can just remove the method.
  $endgroup$
  – Gloweye
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  so how can i use to round in the same logic? 102 -> round to 100, 103 -> round to 5 , 1023 -> 1000, 1044 -> 1050
  $endgroup$
  – jacobcan118
  4 hours ago
  

  
  
  
  

add a comment
 | 

$begingroup$

In short:

• dataclass is the right thing to use as a mutable named tuple. It's basically custom-built to be a great version of that idea.




• Use decimal.Decimal for any financial numbers.




• Don't re-implement round. There's a built-in version that behaves in nice, configurable ways with the Decimal object.




• Not sure what the p.update(**sale=600, **dict(rate=0.9073)) is all about, just use p.update(sale=600, rate=0.9073) (except with Decimals)

share|improve this answer

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

$endgroup$

share|improve this answer

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges

answered 7 hours ago

scnerdscnerd

1,30911 silver badge99 bronze badges