extract values from a data frame based on a vector of row numbers in R

问题

I am trying to extract a vector of values from a data frame based on a vector of row numbers;

df<-iris
x<-c(1,5,15,8,7,2)

I want the corresponding Species of the row numbers listed in the vector x. I have tried something like df$Species[x,] and df$Species[list(x),] to no avail. I am sure the answer is something really simple but I just can't see it!

Thanks in advance

回答1:

Try

df[x,]$Species

or

df[,"Species"][x]

or indeed

df[x,"Species"]

来源：https://stackoverflow.com/questions/17439396/extract-values-from-a-data-frame-based-on-a-vector-of-row-numbers-in-r