passing several arguments to FUN of lapply and others apply

Question

I have a question regarding passing multiple arguments to a function  when using lapply in R    When I use lapply with the syntax of lapply input  myfun   - this is easily understandable  and I can define myfun like that   myfun  lt - function x       doing something here with x    lapply input  myfun     and elements of input are passed as x argument to myfun   But what if I need to pass some more arguments to myfunc  For example  it is defined like that   myfun  lt - function x  arg1       doing something here with x and arg1     How can I use this function with passing both input elements  as x argument  and some other argument

User · Answer

myfun  lt - function x  arg1       doing something here with x and arg1     x is a vector or a list and myfun in lapply x  myfun  is called for each element of x separately   Option 1  If you d like to use whole arg1 in each myfun call  myfun x 1   arg1   myfun x 2   arg1  etc    use lapply x  myfun  arg1   as stated above    Option 2   If you d however like to call myfun to each element of arg1 separately alongside elements of x  myfun x 1   arg1 1    myfun x 2   arg1 2   etc    it s not possible to use lapply  Instead  use mapply myfun  x  arg1   as stated above  or apply    apply cbind x arg1   1  myfun    or   apply rbind x arg1   2  myfun

User · Answer

You can do it in the following way    myfxn  lt - function var1 var2 var3         var1 var2 var3             lapply 1 3 myfxn var2 2 var3 100    and you will get the answer     1    1  200    2    1  400    3    1  600

User · Answer

If you look up the help page  one of the arguments to lapply is the mysterious      When we look at the Arguments section of the help page  we find the following line        optional arguments to    FUN       So all you have to do is include your other argument in the lapply call as an argument  like so   lapply input  myfun  arg1 6    and lapply  recognizing that arg1 is not an argument it knows what to do with  will automatically pass it on to myfun  All the other apply functions can do the same thing   An addendum  You can use     when you re writing your own functions  too  For example  say you write a function that calls plot at some point  and you want to be able to change the plot parameters from your function call  You could include each parameter as an argument in your function  but that s annoying  Instead you can use      as an argument to both your function and the call to plot within it   and have any argument that your function doesn t recognize be automatically passed on to plot

User · Answer

As suggested by Alan  function  mapply  applies a function to multiple Multiple Lists or Vector Arguments   mapply myfun  arg1  arg2    See man page  https   stat ethz ch R-manual R-devel library base html mapply html

[r] passing several arguments to FUN of lapply (and others *apply)

Examples related to r

Examples related to lapply