Remove last N rows in data frame with the arbitrary number of rows
I have a data frame and I want to remove last N rows from it. If I want to remove 5 rows, I currently use the following command, which in my opinion is rather convoluted:
df<- df[-seq(nrow(df),nrow(df)-4),]
How would you accomplish task, is there a convenient function that I can use in R?
In unix, I would use:
tac file | sed '1,5d' | tac
Answer
head with a negative index is convenient for this...
df <- data.frame( a = 1:10 )
head(df,-5)
# a
#1 1
#2 2
#3 3
#4 4
#5 5
p.s. your seq() example may be written slightly less(?) awkwardly using the named arguments by and length.out (shortened to len) like this -seq(nrow(df),by=-1,len=5).