TypeError method takes 1 positional argument but 2 were given

Question

If I have a class     class MyClass       def method arg           print arg       which I use to create an object     my object   MyClass        on which I call method  foo   like so      gt  gt  gt  my object method  foo   Traceback  most recent call last   File   lt stdin gt    line 1  in  lt module gt  TypeError  method   takes exactly 1 positional argument  2 given       why does Python tell me I gave it two arguments  when I only gave one

User · Answer

As mentioned in other answers - when you use an instance method you need to pass self as the first argument - this is the source of the error.

With addition to that,it is important to understand that only instance methods take self as the first argument in order to refer to the instance.

In case the method is Static you don't pass self, but a cls argument instead (or class_).

Please see an example below.

class City:

   country = "USA" # This is a class level attribute which will be shared across all instances  (and not created PER instance)

   def __init__(self, name, location, population):
       self.name       = name
       self.location   = location
       self.population = population
 
   # This is an instance method which takes self as the first argument to refer to the instance 
   def print_population(self, some_nice_sentence_prefix):
       print(some_nice_sentence_prefix +" In " +self.name + " lives " +self.population + " people!")

   # This is a static (class) method which is marked with the @classmethod attribute
   # All class methods must take a class argument as first param. The convention is to name is "cls" but class_ is also ok
   @classmethod
   def change_country(cls, new_country):
       cls.country = new_country

Some tests just to make things more clear:

# Populate objects
city1 = City("New York",    "East", "18,804,000")
city2 = City("Los Angeles", "West", "10,118,800")

#1) Use the instance method: No need to pass "self" - it is passed as the city1 instance
city1.print_population("Did You Know?") # Prints: Did You Know? In New York lives 18,804,000 people!

#2.A) Use the static method in the object
city2.change_country("Canada")

#2.B) Will be reflected in all objects
print("city1.country=",city1.country) # Prints Canada
print("city2.country=",city2.country) # Prints Canada

User · Answer

In simple words   In Python you should add self argument as the first argument to all defined methods in classes   class MyClass    def method self  arg       print arg    Then you can use your method according to your intuition    gt  gt  gt  my object   MyClass    gt  gt  gt  my object method  foo   foo   This should solve your problem     For a better understanding  you can also read the answers to this question  What is the purpose of self

User · Answer

In my case  I forgot to add the     I was calling the method like this  obj   className myMethod   But it should be is like this  obj   className myMethod

User · Answer

Pass cls parameter into  classmethod to resolve this problem    classmethod def test cls       return

User · Answer

You should actually create a class   class accum      def   init   self           self acc   0     def accumulator self  var2add  end           if not end              self acc  var2add     return self acc

User · Answer

Newcomer to Python  I had this issue when I was using the Python s    feature in a wrong way  Trying to call this definition from somewhere   def create properties frame self  parent    kwargs     using a call without a double star was causing the problem   self create properties frame frame  kw gsp       TypeError  create properties frame   takes 2 positional arguments but 3 were given   The solution is to add    to the argument   self create properties frame frame    kw gsp

User · Answer

It occurs when you don t specify the no of parameters the   init     or any other method looking for   For example   class Dog      def   init   self           print  IN INIT METHOD        def   unicode   self            print  IN UNICODE METHOD        def   str   self           print  IN STR METHOD    obj Dog  JIMMY  1 2 3  WOOF     When you run the above programme  it gives you an error like that      TypeError    init     takes 1 positional argument but 6 were given   How we can get rid of this thing   Just pass the parameters  what   init     method looking for   class Dog      def   init   self  dogname  dob d  dob m  dob y  dogSpeakText           self name of dog   dogname         self date of birth   dob d         self month of birth   dob m         self year of birth   dob y         self sound it make   dogSpeakText      def   unicode   self             print  IN UNICODE METHOD        def   str   self           print  IN STR METHOD     obj   Dog  JIMMY   1  2  3   WOOF   print id obj

User · Answer

Something else to consider when this type of error is encountered   I was running into this error message and found this post helpful  Turns out in my case I had overridden an   init     where there was object inheritance   The inherited example is rather long  so I ll skip to a more simple example that doesn t use inheritance   class MyBadInitClass      def    init   self  name           self name   name      def name foo self  arg           print self          print arg          print  My name is   self name    class MyNewClass      def new foo self  arg           print self          print arg    my new object   MyNewClass   my new object new foo  NewFoo   my bad init object   MyBadInitClass name  Test Name   my bad init object name foo  name foo     Result is    lt   main   MyNewClass object at 0x033C48D0 gt  NewFoo Traceback  most recent call last     File  C  Users Orange PycharmProjects Chapter9 bad init example py   line 41  in  lt module gt      my bad init object   MyBadInitClass name  Test Name   TypeError  object   takes no parameters   PyCharm didn t catch this typo  Nor did Notepad    other editors IDE s might    Granted  this is a  takes no parameters  TypeError  it isn t much different than  got two  when expecting one  in terms of object initialization in Python   Addressing the topic  An overloading initializer will be used if syntactically correct  but if not it will be ignored and the built-in used instead  The object won t expect handle this and the error is thrown   In the case of the sytax error  The fix is simple  just edit the custom init statement   def   init   self  name       self name   name

User · Answer

In Python  this   my object method  foo        is syntactic sugar  which the interpreter translates behind the scenes into   MyClass method my object   foo        which  as you can see  does indeed have two arguments - it s just that the first one is implicit  from the point of view of the caller   This is because most methods do some work with the object they re called on  so there needs to be some way for that object to be referred to inside the method  By convention  this first argument is called self inside the method definition   class MyNewClass       def method self  arg           print self          print arg    If you call method  foo   on an instance of MyNewClass  it works as expected    gt  gt  gt  my new object   MyNewClass    gt  gt  gt  my new object method  foo    lt   main   MyNewClass object at 0x29045d0 gt  foo   Occasionally  but not often   you really don t care about the object that your method is bound to  and in that circumstance  you can decorate the method with the builtin staticmethod   function to say so   class MyOtherClass        staticmethod     def method arg           print arg       in which case you don t need to add a self argument to the method definition  and it still works    gt  gt  gt  my other object   MyOtherClass    gt  gt  gt  my other object method  foo   foo

[python] TypeError: method() takes 1 positional argument but 2 were given

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