Returning multiple objects in an R function

Question

How can I return multiple objects in an R function  In Java  I would make a Class  maybe Person which has some private variables and encapsulates  maybe  height  age  etc    But in R  I need to pass around groups of data  For example  how can I make an R function return both an list of characters and an integer

User · Answer

You could use for   with assign   to create many objects   See the example from assign     for i in 1 6     -- Create objects   r 1    r 2        r 6  --     nam  lt - paste  r   i  sep            assign nam  1 i    Looking the new objects  ls pattern     r

User · Answer

Is something along these lines what you are looking for   x1   function x     mu   mean x    l1   list s1 table x  std sd x     return list l1 mu      library Ecdat  data Fair  x1 Fair age

User · Answer

One way to handle this is to put the information as an attribute on the primary one  I must stress  I really think this is the appropriate thing to do only when the two pieces of information are related such that one has information about the other    For example  I sometimes stash the name of  crucial variables  or variables that have been significantly modified by storing a list of variable names as an attribute on the data frame   attr my DF   Modified Variables    lt - DVs For Analysis Names of Modified Vars return my DF    This allows me to store a list of variable names with the data frame itself

User · Answer

You can also use super-assignment   Rather than   lt -  type   lt  lt -   The function will recursively and repeatedly search one functional level higher for an object of that name  If it can t find one  it will create one on the global level

User · Answer

Similarly in Java  you can create a S4 class in R that encapsulates your information   setClass Class  Person            representation              height  numeric               age  numeric                  Then your function can return an instance of this class   myFunction   function age 28  height 176     return new  Person             age age            height height       and you can access your information   aPerson   myFunction    aPerson age aPerson height

User · Answer

Unlike many other languages  R functions don t return multiple objects in the strict sense   The most general way to handle this is to return a list object   So if you have an integer foo and a vector of strings bar in your function  you could create a list that combines these items   foo  lt - 12 bar  lt - c  a    b    e   newList  lt - list  integer    foo   names    bar    Then return this list    After calling your function  you can then access each of these with newList integer or newList names     Other object types might work better for various purposes  but the list object is a good way to get started

[r] Returning multiple objects in an R function

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