What Does "Df[]
Pretty Simple Question, and I Have Had a Quick Search in Google and Stackoverflow. I Found This in Another Post: in Aggregate: Sum Not Meaningful for Factors...
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Pretty simple question, and I have had a quick search in google and stackoverflow. I found this in another post: In aggregate: sum not meaningful for factors.
df[] <- lapply(df, function(x) type.convert(as.character(x)))
how does df[] work?
2 Answers
To add to what Roland wrote,{edit} aaagh he ninja'd me w/ his comment the point is that using DF[] retains the existing object DF with its attributes, in this case the fact that it's got two dimensions and the names a and b .
Rgames> foo<- matrix(1:6,2,3)
Rgames> foo[]<-7:12
Rgames> foo
[,1] [,2] [,3]
[1,] 7 9 11
[2,] 8 10 12
Rgames> foo<-7:12
Rgames> foo
[1] 7 8 9 10 11 12
It invokes [<-.data.frame (i.e., the data.frame method for [<-). That way you assign a list to a data.frame. You could also do
df <- as.data.frame(lapply(df, function(x) type.convert(as.character(x))))
Example:
DF <- data.frame(a=1:2, b=3:4)
DF[] <- list(c=10:11, d=12:13)
# a b
# 1 10 12
# 2 11 13
But compare with this:
DF <- `[<-.data.frame`(DF, , , list(c=c("a", "b"), d=c("d", "e")))
# c d
# 1 a d
# 2 b e
VS. this:
DF <- `[<-.data.frame`(DF, 1:2, 1:2, list(c=c("a", "b"), d=c("d", "e")))
# a b
#1 a d
#2 b e
There is also this:
DF <- as.data.frame(list(c=10:11, d=12:13))
# c d
# 1 10 12
# 2 11 13
Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.
