python - Unix: Getting Mouse -coordinates over X like the Mathematica?

Question

Mathematica

DynamicModule[{list = {}}, 
 EventHandler[
  Dynamic[Framed@
    Graphics[{BSplineCurve[list], Red, Line[list], Point[list]}, 
     PlotRange -> 2]], {{"MouseClicked", 
     1} :> {AppendTo[list, 
      MousePosition["Graphics"]]}}, {"MouseClicked", 2} :> 
   Print[list]]]

I want to do the above at home where I do not have Mathematica. Use whatever tool you want, I like to use Python and R but happy with any solution candidate. The first thing that came to my mind was RStudio and this question here but I am unsure whether some better way to do this.

How can I do the interactive-GUI-innovating over X?

Procedure of the Mathematica -snippet outlined

1. you click points

2. you will see BSplineCurve formating between the points and points are red

3. points are saved to an array

4. when finished, you click `right-mouse-button` so array to stdout

?getGraphicsEvent has some features. As well, one can use RGtk2 (others too) for more event handling. — jverzani
@GSee can you explain how the locator and identify work in R? Perhaps with an example? Even though I read the manuals, I cannot understand the -- tried to find examples such as here but struggling with them, some firing NullPointException etc. — hhh
The best I can do is: library(quantmod); getSymbols("SPY"); chartSeries(SPY); zooom() Then click two places on the chart, and it will zoom in based on where you clicked. So, examine the source of zooom — GSee

Greg Snow Greg Snow · Accepted Answer · 2012-08-22T19:15:41

Here is an R function that does what you describe:

dynmodfunc <- function() {
    plot(0:1,0:1,ann=FALSE,type='n')
    mypoints <- matrix(ncol=2, nrow=0)
    while( length(p <- locator(1, type='p', col='red')) ) {
        mypoints <- rbind(mypoints, unlist(p))
        plot(mypoints, col='red', ann=FALSE, xlim=0:1, ylim=0:1)
        if(nrow(mypoints)>1) {
            xspline(mypoints, shape=-1)
        }
    }
    mypoints
}

(out <- dynmodfunc())

You can change the shape argument to xspline to change the style of spline. This version returns a 2 column matrix with the x and y values, but that could be changed to another structure if prefered. There are plenty of other things that could be customized as well.

Added function to get the output to paste into Mathematica:

matrix2mathematica <- function(x) {
    paste0( '{', 
        paste0( '{', x[,1], ', ', x[,2], '}', collapse=', '),
    '}')
}

cat( matrix2mathematica(out))

python - Unix: Getting Mouse -coordinates over X like the Mathematica?

3 Answers