assign

I see that the Practical Common Lisp uses (defvar *db* nil) for setting up a global variable . Isn't it OK to use setq for the same purpose? What are the advantages/disadvantages of using defvar vs. setq ? There are several ways to introduce variables. DEFVAR and DEFPARAMETER introduce global dynamic variables. DEFVAR optionally sets it to some value, unless it is already defined. DEFPARAMETER sets it always to the provided value. SETQ does not introduce a variable. (defparameter *number-of-processes* 10) (defvar *world* (make-world)) ; the world is made only once. Notice that you likely never

A post on here a day back has me wondering how to assign values to multiple objects in the global environment from within a function. This is my attempt using lapply ( assign may be safer than <<- but I have never actually used it and am not familiar with it). #fake data set df <- data.frame( x.2=rnorm(25), y.2=rnorm(25), g=rep(factor(LETTERS[1:5]), 5) ) #split it into a list of data frames LIST <- split(df, df$g) #pre-allot 5 objects in R with class data.frame() V <- W <- X <- Y <- Z <- data.frame() #attempt to assign the data frames in the LIST to the objects just created lapply(seq_along

I want to assign multiple variables in a single line in R. Is it possible to do something like this? values # initialize some vector of values (a, b) = values[c(2,4)] # assign a and b to values at 2 and 4 indices of 'values' Typically I want to assign about 5-6 variables in a single line, instead of having multiple lines. Is there an alternative? There is a great answer on the Struggling Through Problems Blog This is taken from there, with very minor modifications. USING THE FOLLOWING THREE FUNCTIONS (Plus one for allowing for lists of different sizes) # Generic form '%=%' = function(l, r, ...

Still trying to get into the R logic... what is the "best" way to unpack (on LHS) the results from a function returning multiple values? I can't do this apparently: R> functionReturningTwoValues <- function() { return(c(1, 2)) } R> functionReturningTwoValues() [1] 1 2 R> a, b <- functionReturningTwoValues() Error: unexpected ',' in "a," R> c(a, b) <- functionReturningTwoValues() Error in c(a, b) <- functionReturningTwoValues() : object 'a' not found must I really do the following? R> r <- functionReturningTwoValues() R> a <- r[1]; b <- r[2] or would the R programmer write something more like