How to create a numeric vector of zero length in R

Question

I wonder, how can I create a numeric zero-length vector in R?

I believe it is `numeric(0)`. – Blue Magister Sep 27 '12 at 06:03 — Blue Magister, Sep 27 '12 at 06:03
Do not forget to accept the answer if you liked it! – Ander Biguri Apr 16 '15 at 15:25 — Ander Biguri, Apr 16 '15 at 15:25

mnel · Answer 1 · 2012-09-27T06:29:30.847

112

If you read the help for vector (or numeric or logical or character or integer or double, 'raw' or complex etc ) then you will see that they all have a length (or length.out argument which defaults to 0

Therefore

numeric()
logical()
character()
integer()
double()
raw()
complex() 
vector('numeric')
vector('character')
vector('integer')
vector('double')
vector('raw')
vector('complex')

All return 0 length vectors of the appropriate atomic modes.

# the following will also return objects with length 0
list()
expression()
vector('list')
vector('expression')

edited Sep 27 '12 at 06:29

answered Sep 27 '12 at 06:09

mnel

113,303
27
265
254

1

I apologize for the down vote; it was completely accidental and I only just noticed it had happened. It won't let me change. Sorry. – Stuart R. Jefferys May 11 '13 at 21:26
1

And if the empty vector is intended to hold dates, what would you use? – Zelbinian Dec 16 '15 at 20:43
@Zelbinian That's a curiosity. What are you trying to achieve by doing that? – BroVic Oct 28 '17 at 12:47

score 57 · Answer 2 · answered Sep 27 '12 at 06:04

57

Simply:

x <- vector(mode="numeric", length=0)

answered Sep 27 '12 at 06:04

srctaha

1,394
1
14
16

score 4 · Answer 3 · answered Jun 23 '14 at 14:28

4

Suppose you want to create a vector x whose length is zero. Now let v be any vector.

> v<-c(4,7,8)
> v
[1] 4 7 8
> x<-v[0]
> length(x)
[1] 0

answered Jun 23 '14 at 14:28

Md. Sahidul Islam

563
2
9

1

I don't know what is happening there. Again my answer is mark down. Why??? I want to know explanation. Can anyone give me answer why my answer marks down? – Md. Sahidul Islam Mar 18 '15 at 12:10
You are taking the length of vector element. – upInCloud Sep 13 '15 at 10:17
2

Length is the proven that, the numeric vector (here x) has zero length vector. And x vector is created from any other vector. So x is the desired vector of zero length. Also you should check the heading of the problem clearly? @ShaaradDalvi – Md. Sahidul Islam Sep 14 '15 at 09:13

Aaron McDaid · Answer 4 · 2016-09-28T15:35:51.763

This isn't a very beautiful answer, but it's what I use to create zero-length vectors:

0[-1]     # numeric
""[-1]    # character
TRUE[-1]  # logical
0L[-1]    # integer

A literal is a vector of length 1, and [-1] removes the first element (the only element in this case) from the vector, leaving a vector with zero elements.

As a bonus, if you want a single NA of the respective type:

0[NA]     # numeric
""[NA]    # character
TRUE[NA]  # logical
0L[NA]    # integer

How to create a numeric vector of zero length in R

4 Answers4

Linked

Related