How R does indexing. Every time R shows you a vector, it displays a number such as [1] in front of the output. In this example, [1] tells you where the first position  Here are some examples that show how elements of vectors can be obtained by indexing. b <- 10:15 b ## [1] 10 11 12 13 14 15. Get the first element of a vector.

Here are some examples that show how elements of vectors can be obtained by indexing. b <- 10:15 b ## [1] 10 11 12 13 14 15. Get the first element of a vector. Annual returns[edit]. The "S&P 500" generally quoted is a price return index; there are also "total return" and "net total return"  [code]> x<-rnorm(50) > m<-x>1 > x [1] 0.850151460 -2.006712892 -0.028272640 1.243178124 0.902354859 [6] -0.234300044 -0.066653606 -0.116067659  Character vectors index by name and numeric vectors index by position; use a list to index by position and name at different levels. If a component is not present , 

[code]> x<-rnorm(50) > m<-x>1 > x [1] 0.850151460 -2.006712892 -0.028272640 1.243178124 0.902354859 [6] -0.234300044 -0.066653606 -0.116067659 

return first index for each unique value in a vector I would like to efficiently find the first index of each unique value in a very large vector. For example, if I have a vector A<-c(9,2,9,5) I would like to return not only the unique values (2,5,9) but also their first indices (2,4,1). R Return Value from Function. In this article, you’ll learn to return a value from a function in R. You’ll also learn to use functions without the return function. Many a times, If we want to return multiple values in R, we can use a list (or other objects) and return it. If the index is negative, it would strip the member whose position has the same absolute value as the negative index. For example, the following creates a vector slice with the third member removed. > s[ - 3] is.na() will return a boolean index of the same shape as the original data frame. In other words, any cells in that m x n index with the value TRUE correspond to NA values in the original data frame. You can them use this to change the NAs, if you wish: DF[is.na(DF)] = 999 To get the total number of data rows with at least one NA:

Total Return Index: The total return index is a type of equity index that tracks both the capital gains of a group of stocks over time, and assumes that any cash distributions , such as dividends

As R is optimized to work with vectors, which(x == v)[[1]] is not so very inefficient. It's one comparison (==) operator applied to all vector elements and one subsetting on the indices (which). That's it. Nothing that should be relevant, as long as you're not running 10.000 repetitions on this function. integer-valued index vector, as resulting from which(x)..dim: dim(.) integer vector.dimnames: optional list of character dimnames(.). If useNames is true, to be used for constructing dimnames for arrayInd() (and hence, which(*, arr.ind=TRUE)). If names(.dimnames) is not empty, these are used as column names. .dimnames[[1]] is used as row names. useNames index is a generic function for extracting the index of objects, currently it has a default method and a method for zoo objects which is the same as the time method for zoo objects. Another pair of generic functions provides replacing the index or time attribute. return first index for each unique value in a vector I would like to efficiently find the first index of each unique value in a very large vector. For example, if I have a vector A<-c(9,2,9,5) I would like to return not only the unique values (2,5,9) but also their first indices (2,4,1). R Return Value from Function. In this article, you’ll learn to return a value from a function in R. You’ll also learn to use functions without the return function. Many a times, If we want to return multiple values in R, we can use a list (or other objects) and return it. If the index is negative, it would strip the member whose position has the same absolute value as the negative index. For example, the following creates a vector slice with the third member removed. > s[ - 3]

index is a generic function for extracting the index of objects, currently it has a default method and a method for zoo objects which is the same as the time method for zoo objects. Another pair of generic functions provides replacing the index or time attribute.

The function match works on vectors : x <- sample(1:10) x # [1] 4 5 9 3 8 1 6 10 7 2 match(c(4,8),x) # [1] 1 5. match only returns the first  13 Apr 2018 Yes, we can find the index of an element in a vector as follows: > a <- c(3, 2, -7, -3 , 5, 2) > b <- (a==-7) # this will output a TRUE/FALSE vector >  How to identify the indices of a certain value in a vector - 2 programming examples - match function, which function & %in% operator - Reproducible R code. an ordered vector of the same length as the "index" attribute of x . Details. index is a generic function for extracting the index of objects, currently it has a default 

1 Apr 2015 In this case matrices a and b must have the same number of columns. [v,ka,kb]= intersect(a,b,"r") also returns index vectors ka and kb 

If there are no explicit returns from a function, the value of the last evaluated expression is returned automatically in R. For example, the following is equivalent to the above function. We generally use explicit return() functions to return a value immediately from a function.

R Documentation: Find Maximum Position in Vector Description. Find the maximum position in a vector, breaking ties at random. Usage which.is.max(x) Arguments. x: a vector Details. Ties are broken at random. Value. index of a maximal value. References. Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S.