David,
thank you for your reply

I tried this
attach(mtcars)
interaction.plot(cyl, gear, mpg, type="o", pch=5:8, lty=1 )

but I got this error:
Error in match.arg(type) : 'arg' should be one of "l", "p", "b"

and in ?interaction.plot, "o" it is not listed in type arguments.
Is there any other way to force it to take the argument?

Thanks
Claudio

On Thu, Sep 29, 2011 at 9:00 PM, David Winsemius <dwinsemius@comcast.net>wrote:

>
> On Sep 29, 2011, at 7:22 PM, Heverkuhn Heverkuhn wrote:
>
>  Hello,
>> I was wondering if there is any equivalent of interaction.plot that allow
>> you to set type="o"
>> I tried to use interaction.plot and I have a gap between the symbols of
>> the
>> points and the line.
>>
>>
> If it's OK to have the lines going right though the symbols, then go ahead,
> hack the code. All you need to do is add ,"o" to the type arguments in the
> argument list. The code's not hidden or anything that gets in your way.
>
>
> David Winsemius, MD
> West Hartford, CT
>
>

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