# Re: [R] R-help Digest, Vol 35, Issue 7

From: Uwe Ligges <ligges_at_statistik.uni-dortmund.de>
Date: Mon 09 Jan 2006 - 18:39:06 EST

Evgeniy Kachalin wrote:

```>> Evgeniy Kachalin wrote:
>>
>>> Hello, dear participants!
>>>
>>> Could you tip me, is there any simple and nice way to build
>>> scatter-plot for three different types of data (, and o and * -
>>> signs, for example) with legend.
>>>
>>> Now i can guess only that way:
>>>
>>> plot(x~y,data=subset(mydata,factor1=='1'), pch='.',col='blue')
>>> points(x~y,data=subset(mydata,factor1=='2'), pch='*',col='green')
>>> points(.... etc
>>>
>>> What is the simple and nice way?
>>> Thank you very much for your kindness and help.
>>>
>>
>>
>> Example:
>>
>>
>> with(iris,
>>   plot(Sepal.Length, Sepal.Width, pch = as.integer(Species)))
>> with(iris,
>>   legend(7, 4.4, legend = unique(as.character(Species)),
>>                     pch = unique(as.integer(Species))))
>>
```

>
> Uwe, sorry for my stupid question. You mean that when pch=factor , plot
> can recycle the factor and use it for subscripts or marks.

Yes, it can recycle, but in the example above it does not recycle but takes the whole "Species" vector.

> Then pch=as.integer(Species) results in c(1,2,3) for 3 factor levels.
> And I need symbols 15,16,17 and colors red, blue, green.

What about adding 14 as in as.integer(Species)+14, or 1 for the colors, respectively?

> So then I do:
> iris\$Species->spec.symb
> iris\$Species->spec.col
> levels(spec.symb)<-c(15,16,17)
> levels(spec.col)<-c('red','green','blue')
>
> That's the only way?

This is one qay of many.

> More of that!!! 'Plot' does not like factors in 'pch'. So it must be so:
> plot(x~y,data, pch=as.integer(as.character(spec.symb))).
> That's totally crazy...

You can set up your own pch variable of course, if you don't like it this fast and easy way.

Uwe Ligges

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