[R] Customise a symbol in a scatterplot with for loop

[Jim Lemon]

On 03/24/2014 07:00 AM, amcc wrote:
> Hi,
> I have the code below to generate a pentagon in R.  I have generated a
> regular scatterplot and need to draw a scatterplot with a pentagon at each
> (x,y) position, for the radius use r x 0.3.  The hint I've been given is
> that I do not need to store the polygons in a list, simply construct and
> draw the polygons within a for loop.  Four hours have gone by and I'm no
> closer, so any help would be appreciated.  My original scatterplot code is
>
> plot(Sepal.Width~Sepal.Length, data=iriss)
>
> mk_pent<-
>   function(x,y,r){
>    angle<-(0:4)*360/5+90
>    angle<-angle*pi/180
>    xs<-r*cos(angle)+x
>    ys<-r*sin(angle)+y
>   cbind(x=xs,y=ys)}

Hi A,
Your function is almost there, it just doesn't close the pentagon. You 
might think of drawing the lines within the function to make things 
easier. Once you can successfully draw a pentagon on an existing plot, 
you can work out how to pass your x and y coordinates successively to it 
within the for loop.

Jim