I am trying to coerce all the columns in a data frame as 'numeric' as a step previous to run lm() over it. One of the columns is read by R as a 'character', so I tried this:
df <- data_frame
for (i in colnames(df)){
if (is.numeric(df[i]) == FALSE){
df[i] == as.numeric(df[i])
}
}
And I get this error:
Error in as.numeric(df[i]) : 'list' object cannot be coerced to type 'double'
Any ideas about what's happening?
As @s_baldur states in his comment, you need double [[ to extract an item's list as a vector. [ merely subsets the original list, i.e., it returns a list:
> my_list <- list(X = c("A", "B"),
Y = 1:2,
Z = c(TRUE, FALSE))
> my_list[1]
$X
[1] "A" "B"
> class(my_list[1])
[1] "list"
> my_list[1:2]
$X
[1] "A" "B"
$Y
[1] 1 2
> class(my_list[1:2])
[1] "list"
> my_list[[1]]
[1] "A" "B"
> class(my_list[[1]])
[1] "character"
