# For Loop in R

For is a keyword reserved for a loop statement. The for loop executes a block of statements continuously as long as the condition of the loop is true. The loop stops only when the condition is false. Thus, the block of codes executes only a specified number of times over a sequence (dictionary, string, list, set or tuple).

### Syntax:

for (value in vector) { statements }

### Example 1:

var <- LETTERS[1:10] for ( i in var) { print(i) }

Output:

[1] "A"   [1] "B"   [1] "C"   [1] "D"   [1] "E"   [1] "F"   [1] "G"   [1] "H"   [1] "I"   [1] "J"

### Example 2:

even <- c(2,4,6,8)   for (i in even) { print(i) }

Output:

[1] 2   [1] 4   [1] 6   [1] 8

### Example 3:

colors <- list("red", "yellow", "blue", "white", "pink", "green")   for (x in colors) { print(x) }

Output:

[1] "red"   [1] "yellow"   [1] "blue"   [1] "white"   [1] "pink"   [1] "green"

### Example 4:

dice <- 1:6   for (x in dice) { if (x == 6) { cat("\n\nRolling Dice =", x, "\nWINNER!!") } else { cat("\nRolling Dice =", x, "\nTry Again!") } }

Output:

Rolling Dice = 1   Try Again!   Rolling Dice = 2   Try Again!   Rolling Dice = 3   Try Again!   Rolling Dice = 4   Try Again!   Rolling Dice = 5   Try Again!   Rolling Dice = 6   WINNER!!

### Example 5:

var <- 1:10 for (i in var) { if (i == 3){ next } print(i) }

Output:

[1] 1   [1] 2   [1] 4   [1] 5   [1] 6   [1] 7   [1] 8   [1] 9   [1] 10

### Example 6:

var <- c(11,22,33,44,55,66,77,88,99,-100) sum <- 0 for(n in var){ if(n<0){ next } sum = sum + n } cat("Sum of all +ve numbers in var =",sum)

Output:

Sum of all +ve numbers in var = 495

### Example 7:

var <- LETTERS[1:9] for ( i in var) { if (i == "F") { next } print(i) }

Output:

[1] "A"   [1] "B"   [1] "C"   [1] "D"   [1] "E"   [1] "G"   [1] "H"   [1] "I"

### Example 8:

bag <- list("bottle", "lunch", "books", "pen")   for (item in bag) { if (item == "lunch") { next } print(item) }

Output:

[1] "bottle"   [1] "books"   [1] "pen"

### Example 9:

bag <- list("bottle", "books", "lunch", "pen")   for (x in bag) { if (x == "lunch") { break } print(x) }

Output:

[1] "bottle"   [1] "books"

### Example 10:

colors <- list("red", "yellow", "pink", "white")   items <- list("flower", "rose", "cap") for (x in colors) { for (y in items) { if (y == "cap") { break } print(paste(x, y)) } }

Output:

[1] "red flower"   [1] "red rose"   [1] "yellow flower"   [1] "yellow rose"   [1] "pink flower"   [1] "pink rose"   [1] "white flower"   [1] "white rose"

### Example 11:

for (odd in c(1,3,5,9,11)) { for (i in c(1,3)) { if (odd==11) break print(odd) } }

Output:

[1] 1   [1] 1   [1] 3   [1] 3   [1] 5   [1] 5   [1] 9   [1] 9

### Example 12:

N = 23 temp = 0 if(N > 1) { temp = 1 for(i in 2:(N-1)) { if ((N %% i) == 0) { temp = 0 break } } } if(N == 2) temp = 1 if(temp == 1) { print(paste(N,"is a Prime Number.")) } else { print(paste(N,"is not a Prime Number.")) }

Output:

[1] "23 is a Prime Number."