Dear all,
I want to assign a list to one column of data.frame where the name of the column
is a variable. I tried the following:
Using R version 3.3.2
> df <- iris[1:3, ]
> df
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# 1 5.1 3.5 1.4 0.2 setosa
# 2 4.9 3.0 1.4 0.2 setosa
# 3 4.7 3.2 1.3 0.2 setosa
> mylist <- list(c(1,2,3),c(1),c())
> mylist
# [[1]]
# [1] 1 2 3
#
# [[2]]
# [1] 1
#
# [[3]]
# NULL
> n1 <- 'new1'
> df$n1 <- mylist
> n2 <- 'new2'
> df[,n2] <- mylist
# Warning message:
# In `[<-.data.frame`(`*tmp*`, , "new4", value = list(c(1, 2, 3), :
# provided 3 variables to replace 1 variables
> n3 <- 'new3'
> df[,n3] <- I(mylist)
# Warning message:
# In `[<-.data.frame`(`*tmp*`, , "new3", value = list(c(1, 2, 3), :
# provided 3 variables to replace 1 variables
> eval(parse(text = paste0("df$","new4","<- mylist")))
> df
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species n1 new2 new3
new4
# 1 5.1 3.5 1.4 0.2 setosa 1, 2, 3 1 1
1, 2, 3
# 2 4.9 3.0 1.4 0.2 setosa 1 2 2
1
# 3 4.7 3.2 1.3 0.2 setosa NULL 3 3
NULL
The "eval" works correctly, however, if I want to avoid using "eval", what
should I do?
Thanks!
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