How does Python return multiple values from a function

Question

I have written the following code   class FigureOut     def setName self  name         fullname   name split         self first name   fullname 0        self last name   fullname 1      def getName self         return self first name  self last name  f   FigureOut   f setName  Allen Solly   name   f getName   print  name    I get the following Output     Allen    Solly     Whenever multiple values are returned from a function in python  does it always convert the multiple values to a list of multiple values and then returns it from the function   Is the whole process same as converting the multiple values to a list explicitly and then returning the list  for example in JAVA  as one can return only one object from a function in JAVA

User · Answer

Whenever multiple values are returned from a function in python, does it always convert the multiple values to a list of multiple values and then returns it from the function??

I'm just adding a name and print the result that returns from the function. the type of result is 'tuple'.

  class FigureOut:
   first_name = None
   last_name = None
   def setName(self, name):
      fullname = name.split()
      self.first_name = fullname[0]
      self.last_name = fullname[1]
      self.special_name = fullname[2]
   def getName(self):
      return self.first_name, self.last_name, self.special_name

f = FigureOut()
f.setName("Allen Solly Jun")
name = f.getName()
print type(name)

I don't know whether you have heard about 'first class function'. Python is the language that has 'first class function'

I hope my answer could help you. Happy coding.

User · Answer

From Python Cookbook v 30  def myfun        return 1  2  3     a  b  c   myfun        Although it looks like myfun   returns multiple values  a tuple is actually being created  It looks a bit peculiar  but it   s actually the comma that forms a tuple  not the parentheses   So yes  what s going on in Python is an internal transformation from multiple comma separated values to a tuple and vice-versa    Though there s no equivalent in java you can easily create this behaviour using array s or some Collections like Lists   private static int   sumAndRest int x  int y        int   toReturn   new int 2        toReturn 0    x   y      toReturn 1    x - y       return toReturn       Executed in this way   public static void main String   args        int   results   sumAndRest 10  5        int sum    results 0       int rest   results 1        System out println  sum       sum     nrest       rest        result   sum   15 rest   5

User · Answer

Here It is actually returning tuple   If you execute this code in Python 3    def get        a   3     b   5     return a b number   get   print type number   print number    Output      lt class  tuple  gt   3  5    But if you change the code line return  a b  instead of return a b and execute     def get        a   3     b   5     return  a b  number   get   print type number   print number    Output     lt class  list  gt   3  5    It is only returning single object which contains multiple values    There is another alternative to return statement for returning multiple values  use yield  to check in details see this What does the  quot yield quot  keyword do in Python    Sample Example    def get        for i in range 5           yield i number   get   print type number   print number  for i in number      print i    Output     lt class  generator  gt   lt generator object get at 0x7fbe5a1698b8 gt  0 1 2 3 4

User · Answer

Since the return statement in getName specifies multiple elements   def getName self      return self first name  self last name   Python will return a container object that basically contains them    In this case  returning a comma separated set of elements creates a tuple  Multiple values can only be returned inside containers   Let s use a simpler function that returns multiple values   def foo a  b       return a  b   You can look at the byte code generated by using dis dis  a disassembler for Python bytecode  For comma separated values w o any brackets  it looks like this    gt  gt  gt  import dis  gt  gt  gt  def foo a  b           return a b          gt  gt  gt  dis dis foo    2           0 LOAD FAST                0  a                3 LOAD FAST                1  b                6 BUILD TUPLE              2               9 RETURN VALUE   As you can see the values are first loaded on the internal stack with LOAD FAST and then a BUILD TUPLE  grabbing the previous 2 elements placed on the stack  is generated  Python knows to create a tuple due to the commas being present   You could alternatively specify another return type  for example a list  by using     For this case  a BUILD LIST is going to be issued following the same semantics as it s tuple equivalent    gt  gt  gt  def foo list a  b           return  a  b   gt  gt  gt  dis dis foo list    2           0 LOAD FAST                0  a                3 LOAD FAST                1  b                6 BUILD LIST               2               9 RETURN VALUE   The type of object returned really depends on the presence of brackets  for tuples    can be omitted if there s at least one comma      creates lists and    sets  Dictionaries need key val pairs   To summarize  one actual object is returned  If that object is of a container type  it can contain multiple values giving the impression of multiple results returned  The usual method then is to unpack them directly    gt  gt  gt  first name  last name   f getName    gt  gt  gt  print  first name  last name      As an aside to all this  your Java ways are leaking into Python  -    Don t use getters when writing classes in Python  use properties  Properties are the idiomatic way to manage attributes  for more on these  see a nice answer here

User · Answer

Python functions always return a unique value  The comma operator is the constructor of tuples so self first name  self last name evaluates to a tuple and that tuple is the actual value the function is returning

User · Answer

mentioned also here  you can use this   import collections Point   collections namedtuple  Point     x    y    p   Point 1  y 2   gt  gt  gt  p x  p y 1 2  gt  gt  gt  p 0   p 1  1 2

[python] How does Python return multiple values from a function?

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