ciclos en R for while repeat

• for(var in seq) expr
• while(cond) expr
• repeat expr
• break
• next

Sintaxis

• for(var in seq) expr
• var es nombre de variable
• seq una expresión que indica una secuencia (puede ser un vector, una lista )
• expr Una expresión en sentido formal

for (i in 1:10) {

# Recorre una secuencia desde hasta 10 de uno en uno
for (i in 1:10) {
  print (i)
}

## [1] 1
## [1] 2
## [1] 3
## [1] 4
## [1] 5
## [1] 6
## [1] 7
## [1] 8
## [1] 9
## [1] 10

for (i in 1:fin) {

# Recorre una secuencia desde hasta 20 de uno en uno
fin <- 20
for (i in 1:fin) {
  print (i)
}

## [1] 1
## [1] 2
## [1] 3
## [1] 4
## [1] 5
## [1] 6
## [1] 7
## [1] 8
## [1] 9
## [1] 10
## [1] 11
## [1] 12
## [1] 13
## [1] 14
## [1] 15
## [1] 16
## [1] 17
## [1] 18
## [1] 19
## [1] 20

for (n in c(2,5,10,20,50)) {

#Recorre los valores contenidos en el vector
for (n in c(2,5,10,20,50)) {
print(n)
}

## [1] 2
## [1] 5
## [1] 10
## [1] 20
## [1] 50

Recorre las letras

existe una constante predefinida llamada

letter o LETTER

letters # Son valores constantes que existenen R

##  [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q"
## [18] "r" "s" "t" "u" "v" "w" "x" "y" "z"

LETTERS # Son valores constantes que existenen R

##  [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q"
## [18] "R" "S" "T" "U" "V" "W" "X" "Y" "Z"

for (l in letters) {
  print(l)
}

## [1] "a"
## [1] "b"
## [1] "c"
## [1] "d"
## [1] "e"
## [1] "f"
## [1] "g"
## [1] "h"
## [1] "i"
## [1] "j"
## [1] "k"
## [1] "l"
## [1] "m"
## [1] "n"
## [1] "o"
## [1] "p"
## [1] "q"
## [1] "r"
## [1] "s"
## [1] "t"
## [1] "u"
## [1] "v"
## [1] "w"
## [1] "x"
## [1] "y"
## [1] "z"

for (l in LETTERS) {
  print(l)
}

## [1] "A"
## [1] "B"
## [1] "C"
## [1] "D"
## [1] "E"
## [1] "F"
## [1] "G"
## [1] "H"
## [1] "I"
## [1] "J"
## [1] "K"
## [1] "L"
## [1] "M"
## [1] "N"
## [1] "O"
## [1] "P"
## [1] "Q"
## [1] "R"
## [1] "S"
## [1] "T"
## [1] "U"
## [1] "V"
## [1] "W"
## [1] "X"
## [1] "Y"
## [1] "Z"

while

while (TRUE) {

i <- 0
while (TRUE) {
  if (i == 10) 
    break
  else {
    i <- i+1
    print(i)
  }    
}

## [1] 1
## [1] 2
## [1] 3
## [1] 4
## [1] 5
## [1] 6
## [1] 7
## [1] 8
## [1] 9
## [1] 10

while ( i < 10)

i <- 0
while ( i < 10) {
  if (i == 10) 
    break
  else {
    i <- i+1
    print(i)
  }    
}

## [1] 1
## [1] 2
## [1] 3
## [1] 4
## [1] 5
## [1] 6
## [1] 7
## [1] 8
## [1] 9
## [1] 10

repeat

Sintaxis

• repeat expr

repeat {if (salir) break }

repeat {
print ('hola')
salir <- TRUE
if (salir) break 
}

## [1] "hola"

if (TRUE)

repeat {
print ('hola')

if (TRUE) 
  break 
}

## [1] "hola"