The following code should not work, should it?
plot(1:10,1:10,main="",)
(There is an "illegal" comma at the end, right?)
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3You'll need to tag what language you're using here so that the right people can come look and answer. I'm sure its valid in some language somewhere and not in others. ;-)Chris– Chris2014-07-21 13:29:50 +00:00Commented Jul 21, 2014 at 13:29
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Looks like MATLAB, or maybe R, but OP needs to clarify ASAP.Paul R– Paul R2014-07-21 13:30:30 +00:00Commented Jul 21, 2014 at 13:30
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I do apologise - that's what happens when you only use one language!Ketil B T– Ketil B T2014-07-23 08:09:22 +00:00Commented Jul 23, 2014 at 8:09
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1 Answer
The syntax of this statement is not illegal. R will use the parameter's default value if you provide an "empty" argument.
For example, the rnorm function takes three arguments. The latter two have default values:
rnorm(n, mean = 0, sd = 1)
The expressions
rnorm(10)
rnorm(10, )
rnorm(10, , )
are identical. However, if you add an additional comma (and therefore an additional argument), the command will fail:
rnorm(10, , , )
# Error in rnorm(10, , , ) : unused argument ()
8 Comments
Sven Hohenstein
@DavidArenburg In the case of an numeric argument, the
plot.default function is used. This function has many default values.
David Arenburg
So why
plot(,5) doesn't work but plot(5) does, while essentially it puts 5 in the y axisSven Hohenstein
@DavidArenburg The
plot.default function has no default value for the first argument. If you omit the second argument, NULL is used by default. Have a look at the code of the function to see how this special case is treated.David Arenburg
Actually it more complicated than that, apparently the
xy.coords comes in and tries to interpret it in a meaningful way, see Details in ?xy.coords (just found out it my self)Sven Hohenstein
@DavidArenburg In
xy.coords the default value for y is also NULL. |