Beginner Python AttributeError list object has no attribute

Question

The error says   AttributeError   list  object has no attribute  cost     I am trying to get a simple profit calculation to work using the following class to handle a dictionary of bicycles   class Bike object       def   init   self  name  weight  cost           self name   name         self weight   weight         self cost   cost  bikes           Bike designed for children       Trike     Trike   20  100         Bike designed for everyone       Kruzer     Kruzer   50  165          When I try to calculate profit with my for statement  I get the attribute error     Markup of 20  on all sales margin    2   Revenue minus cost after sale for bike in bikes values        profit   bike cost   margin   First  I don t know why it is referring to a list  and everything seems to be defined  no

User · Answer

They are lists because you type them as lists in the dictionary:

bikes = {
    # Bike designed for children"
    "Trike": ["Trike", 20, 100],
    # Bike designed for everyone"
    "Kruzer": ["Kruzer", 50, 165]
    }

You should use the bike-class instead:

bikes = {
    # Bike designed for children"
    "Trike": Bike("Trike", 20, 100),
    # Bike designed for everyone"
    "Kruzer": Bike("Kruzer", 50, 165)
    }

This will allow you to get the cost of the bikes with bike.cost as you were trying to.

for bike in bikes.values():
    profit = bike.cost * margin
    print(bike.name + " : " + str(profit))

This will now print:

Kruzer : 33.0
Trike : 20.0

User · Answer

You need to pass the values of the dict into the Bike constructor before using like that  Or  see the namedtuple -- seems more in line with what you re trying to do

User · Answer

Consider   class Bike object       def   init   self  name  weight  cost           self name   name         self weight   weight         self cost   cost  bikes           Bike designed for children       Trike   Bike  Trike   20  100           lt --       Bike designed for everyone       Kruzer   Bike  Kruzer   50  165         lt --          Markup of 20  on all sales margin    2   Revenue minus cost after sale for bike in bikes values        profit   bike cost   margin     print profit    Output    33 0 20 0   The difference is that in your bikes dictionary  you re initializing the values as lists         Instead  it looks like the rest of your code wants Bike instances   So create Bike instances  Bike        As for your error   AttributeError   list  object has no attribute  cost    this will occur when you try to call  cost on a list object   Pretty straightforward  but we can figure out what happened by looking at where you call  cost -- in this line   profit   bike cost   margin   This indicates that at least one bike  that is  a member of bikes values   is a list    If you look at where you defined bikes you can see that the values were  in fact  lists   So this error makes sense   But since your class has a cost attribute  it looked like you were trying to use Bike instances as values  so I made that little change         - gt  Bike        and you re all set

[python] Beginner Python: AttributeError: 'list' object has no attribute

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