[R] Mass 'identify' on 2d-plot

[Evgeniy Kachalin]

Barry Rowlingson Ð¿Ð¸ÑˆÐµÑ‚:
> Evgeniy Kachalin wrote:
> 
>> What is ability in R to graphically (per mouse) define some area and 
>> to select all the cases felt in it?
>>
>> 'identify' is OK for 5-10 cases, but what if cases=1000?
> 
> 
>  You can use 'locator' to let the user click a number of points to 
> define a polygon, and then use one of the point-in-polygon functions 
> provided by one of the spatial packages to work out whats in your polygon.
> 
>  Look at splancs, spatstat, sp - pretty much anything beginning with 
> 'sp' - on CRAN.
> 
>  In splancs you can just do:
> 
>  poly = getpoly()
> 
>  - which lets the user draw a polygon on screen, then:
> 
>  inPoly = inpip(xypts,poly)
>  points(xypts[inpip,], pch=19,col="red")
> 
>  and that will plot the selected points in solid red dots.
> 
>  I don't think there's a way to draw a freehand figure on an R plot, you 
> have to go click, click, click, and draw straight lines.
> 

I don't get what is 'xypts' in this case... One step earlier i've 
plotted plot(y~x,data=dat). What is xypts?

-- 
Evgeniy Kachalin