In R, the which() function gives you the position of elements of a logical vector that are TRUE.
1. which(letters=="z") returns 26.
Examples
1. which(letters=="z") returns 26.
Create a simple data frame
ls = data.frame( x1 = ceiling(runif(10)*10),
x2 = ceiling(runif(10)*10),
x3 = runif(10),
x4= rep(letters[1:5],2))
 |
| Sample Data Frame |
2. Column number of variable "x4" in ls data set
i=which(names(ls)== "x4")
3. Row number in which maximum value of variable "x1"exists
which(ls$x1 == max(ls$x1))4. Row number in which conditions hold true
which(ls$x1 == 7 & ls$x2 == 4)
5. Number of cases in which variable x1 is equal to variable x2
7. Extract names of all the numeric variableslength(which(ls$x1 == ls$x2))6. Which value is common in both the variables
ls[which(ls$x1 == ls$x2),"x1"]
check = which(sapply(ls, is.numeric))
colnames(ls)[check]