In practical terms there seems to be no difference, but underneath the cloth as the language processes is there any difference?
Is there a difference between assigning value using '-' or '=' in R?
8
asked by anonymous 20.10.2016 / 01:17
2 answers
6
Complementing Marcus's answer. An interesting point is the precedence of these operators. <- comes before = . What causes:
> a <- b = 1
Error in a <- b = 1 : não foi possível encontrar a função "<-<-"
Do not work, but:
> a = b <- 1
> a
[1] 1
> b
[1] 1
Run.
This is the only case I've seen that gives an error ... But as it is very unusual, it ends up whatever it is used for.
In fact, I just saw that this example is in the pecedence link .
## '=' has lower precedence than '<-' ... so you should not mix them ## (and '<-' is considered better style anyway): ## Consequently, this gives a ("non-catchable") error x <- y = 5 #-> Error in (x <- y) = 5 : ....
If you link to code style, most books recommend using <- . Example:
Assignment Use
20.10.2016 / 12:51
7
There is no difference in the vast majority of cases. The commands
x <- 5
and
x = 5
are identical.
However, if you want to assign arguments to a function, you are required to use = . For example, to generate a sample of 10 observations of a normal random variable with mean 5 and standard deviation 2, only the
rnorm(10, mean = 5, sd = 2)
It works. It's no use trying to run
rnorm(10, mean <- 5, sd <- 2)
You will not get the desired result.
In particular, I'd rather use <- whenever I'm going to assign some value to an object. I find it more elegant because it differs from assigning arguments to functions. But it's just a matter of style.
20.10.2016 / 01:42