I created a data frame from an aggregate - function. The length of the data-frame is two. However when I print the data-frame out 5 columns appear. How does R handle headers and sub headers in a data frame? How can I get rid of the first level of headers if this is the case here?
d <- data.frame("User id"=c(1,1,2,3,1),
block=c("north","south","east","west","south"), check.names = F)
f <- function(l, vec) {
vec[l] <- 1
vec
}
vec <- setNames(rep(0, 4), levels(d$block))
df <- aggregate(block~`User id`, d, f, vec)
These are the outputs that confuse me:
>names(df)
[1] "User id" "block"
> df
User id block.east block.north block.south block.west
1 1 0 1 1 0
2 2 1 0 0 0
3 3 0 0 0 1
This is what I want to have:
> names(df)
> "User id" "block.east" "block.north" "block.south" "block.west"
We can do this more easily with table
out <- as.data.frame.matrix(+(table(d) > 0))
names(df) <- paste0("block.", names(df))
Regarding the issue in OP's output, it is a matrix
column,
str(df)
#'data.frame': 3 obs. of 2 variables:
# $ User id: num 1 2 3
# $ block : num [1:3, 1:4] 0 1 0 1 0 0 1 0 0 0 ...
# ..- attr(*, "dimnames")=List of 2
# .. ..$ : NULL
# .. ..$ : chr "east" "north" "south" "west"
so we can convert to regular data.frame with
df <- do.call(data.frame, df)
names(df)
#[1] "User.id" "block.east" "block.north" "block.south" "block.west"
str(df)
#'data.frame': 3 obs. of 5 variables:
# $ User.id : num 1 2 3
# $ block.east : num 0 1 0
# $ block.north: num 1 0 0
# $ block.south: num 1 0 0
# $ block.west : num 0 0 1
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