r - How to create new columns in data.frame on the fly? -


similar question

how name variables on fly?

basically want create new column in data.frame on go. might bad practice, i'm doing solution.

right i've tried :

test <- iris create.new_var <- function(x) {   assign(paste("test$", x, sep=""), test$petal.width)   return(test) }  test <- create.new.var('cheese')

the function runs without breaking. data.frame test not contain new column heading 'cheese' , values of iris$petal.width 1 imagine should.

using assign kind of operations not recommended. but, if need try assign, possible option is

 create.new_var <- function(x){   assign('test', `[[<-`(test, x, value=test$petal.width), envir=.globalenv)  }  test <- create.new_var('cheese')  head(test,3)  #  sepal.length sepal.width petal.length petal.width species cheese  #1          5.1         3.5          1.4         0.2  setosa    0.2  #2          4.9         3.0          1.4         0.2  setosa    0.2  #3          4.7         3.2          1.3         0.2  setosa    0.2

you can add data , replacement column argument in function

create.new_var <- function(dat, x, x1){   str1 <- deparse(substitute(dat))   assign(str1, `[[<-`(dat, x, value=dat[,x1]), envir=.globalenv) }  test <- create.new_var(test, 'cheese', 'petal.width')

here option without using assign, or paste (some deleted posts used similar method).

 create.new_var2 <- function(dat, x, x1){                         dat[,x] <- dat[,x1]                        dat}   create.new_var2(test, 'cheese', 'petal.width')

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