How to make R skip for 2:n cycle in case n = 1?

I have the next query.
I have a cycle

for (i in 2:n) { ... }

and it executes twice in case n = 1 for i equals 2 and then for 1, but I want this cycle isn't been executed at all in such case.
I've also tried

seq(from = 2, to = 1, by = 1)

but it generates exception.

I guess than common question, but I am new in that language and wasn't able to bypass it or find workaround in internet.
Thank you in advance.

asked Jan 1 at 13:24

LinearLeopard

981111

2

: or seq don't work that way. You could use the length.out param in seq: seq(from = 2, to = n,length.out = (n-2)+1)

– Omri374
Jan 1 at 13:37

add a comment |

I have the next query.
I have a cycle

for (i in 2:n) { ... }

and it executes twice in case n = 1 for i equals 2 and then for 1, but I want this cycle isn't been executed at all in such case.
I've also tried

seq(from = 2, to = 1, by = 1)

but it generates exception.

I guess than common question, but I am new in that language and wasn't able to bypass it or find workaround in internet.
Thank you in advance.

asked Jan 1 at 13:24

LinearLeopard

981111

2

: or seq don't work that way. You could use the length.out param in seq: seq(from = 2, to = n,length.out = (n-2)+1)

– Omri374
Jan 1 at 13:37

add a comment |

I have the next query.
I have a cycle

for (i in 2:n) { ... }

and it executes twice in case n = 1 for i equals 2 and then for 1, but I want this cycle isn't been executed at all in such case.
I've also tried

seq(from = 2, to = 1, by = 1)

but it generates exception.

I guess than common question, but I am new in that language and wasn't able to bypass it or find workaround in internet.
Thank you in advance.

asked Jan 1 at 13:24

LinearLeopard

981111

I have the next query.
I have a cycle

for (i in 2:n) { ... }

and it executes twice in case n = 1 for i equals 2 and then for 1, but I want this cycle isn't been executed at all in such case.
I've also tried

seq(from = 2, to = 1, by = 1)

but it generates exception.

I guess than common question, but I am new in that language and wasn't able to bypass it or find workaround in internet.
Thank you in advance.

r range

asked Jan 1 at 13:24

LinearLeopard

981111

asked Jan 1 at 13:24

LinearLeopard

981111

asked Jan 1 at 13:24

LinearLeopard

981111

asked Jan 1 at 13:24

LinearLeopard

981111

asked Jan 1 at 13:24

LinearLeopard

981111

2

: or seq don't work that way. You could use the length.out param in seq: seq(from = 2, to = n,length.out = (n-2)+1)

– Omri374
Jan 1 at 13:37

add a comment |

2

: or seq don't work that way. You could use the length.out param in seq: seq(from = 2, to = n,length.out = (n-2)+1)

– Omri374
Jan 1 at 13:37

: or seq don't work that way. You could use the length.out param in seq: seq(from = 2, to = n,length.out = (n-2)+1)

– Omri374
Jan 1 at 13:37

add a comment |

1 Answer
1

active

oldest

votes

Use seq_len which is safer to use

n <- 1

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Does not print anything



n <- 4

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Check 2 

#Check 3 

#Check 4

When you use 2:n and when n = 1 it gives

2:1

#[1] 2 1

hence, it runs the loop twice.

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

2

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

Use seq_len which is safer to use

n <- 1

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Does not print anything



n <- 4

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Check 2 

#Check 3 

#Check 4

When you use 2:n and when n = 1 it gives

2:1

#[1] 2 1

hence, it runs the loop twice.

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

2

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

add a comment |

Use seq_len which is safer to use

n <- 1

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Does not print anything



n <- 4

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Check 2 

#Check 3 

#Check 4

When you use 2:n and when n = 1 it gives

2:1

#[1] 2 1

hence, it runs the loop twice.

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

2

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

add a comment |

Use seq_len which is safer to use

n <- 1

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Does not print anything



n <- 4

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Check 2 

#Check 3 

#Check 4

When you use 2:n and when n = 1 it gives

2:1

#[1] 2 1

hence, it runs the loop twice.

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

Use seq_len which is safer to use

n <- 1

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Does not print anything



n <- 4

for (i in seq_len(n)[-1]) {

  cat("Check", i, "n")

}



#Check 2 

#Check 3 

#Check 4

When you use 2:n and when n = 1 it gives

2:1

#[1] 2 1

hence, it runs the loop twice.

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

answered Jan 1 at 13:33

Ronak Shah

39.8k104162

2

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

add a comment |

2

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

I made a stupid mistake. It should be seq_len(n-1) + 1.

– mt1022
Jan 1 at 14:51

add a comment |

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