How to get index in a loop in R

Question

I have a vector of character type which has all the list of names.

So I'm looping through each name and peforming some actions. This loop is not based on the index/length (and I want to keep it this way).

However, if I want to access the index value in the loop how do I get it.

Ex:

names <- c("name1", "name2")  for(name in names){  #do something print(name)  #here how would I get the index number? like 1, 2 etc?  } 

Answer 1

You can do something like this, which is literally getting the i value.

names <- c("name1", "name2") i<-0 for(name in names){     i<-i+1     print(i)  } 

Or change the loop to use a numeric index

names <- c("name1", "name2") for(i in 1:length(names)){     print(i)  } 

Or use the which function.

names <- c("name1", "name2") for(name in names){      print(which(name == names))  } 

Answer 2

For variety:

names <- c("name1", "name2") for(i in seq_along(names)){     print(i) } 

seq_along is a fast primitive, and IMO slightly sweeter syntactic sugar.