Optimisation: sort or order and indicating default parameter

First, it is better to use sort(x) or x[order(x)]:

> x <- sample(1:100, 100)
> system.time({
+   for (i in 1:100000) y <- x[order(x, decreasing = FALSE)]
+ })
utilisateur     système      écoulé
      1.908       0.043       1.965
> system.time({
+   for (i in 1:100000) y <- sort(x, decreasing = FALSE)
+ })
utilisateur     système      écoulé
      2.993       0.035       3.043

Clearly the syntax x[order(x)] is more rapid (1/3 more fast).

 Now a second test: decreasing = FALSE is the default; what is the difference if it is not indicated:

> system.time({
+   for (i in 1:100000) y <- x[order(x)]
+ })
utilisateur     système      écoulé
      1.907       0.037       1.952
>
> system.time({
+   for (i in 1:100000) y <- sort(x)
+ })
utilisateur     système      écoulé
      3.049       0.035       3.094

No big change...

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