# Tcl/Tk GUI Example with Variable Input by User

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I recently used R with GUI-elements for the first time and browsed through the available online resources, but I didn’t quite find what I was searching for: The user should be able to put in some variables and call a function with a button. In the end I did it with a little help from SO. Here is the working example that I eventually plugged together:

require(tcltk) mydialog <- function(){ xvar <- tclVar("") yvar <- tclVar("") zvar <- tclVar("") tt <- tktoplevel() tkwm.title(tt,"MYTEST") x.entry <- tkentry(tt, textvariable=xvar) y.entry <- tkentry(tt, textvariable=yvar) z.entry <- tkentry(tt, textvariable=zvar) reset <- function() { tclvalue(xvar)<-"" tclvalue(yvar)<-"" tclvalue(zvar)<-"" } reset.but <- tkbutton(tt, text="Reset", command=reset) submit <- function() { x <- as.numeric(tclvalue(xvar)) y <- as.numeric(tclvalue(yvar)) z <- as.numeric(tclvalue(zvar)) tkmessageBox(message=paste("x + y + z = ", x+y+z, "")) } submit.but <- tkbutton(tt, text="submit", command=submit) quit.but <- tkbutton(tt, text = "Close Session", command = function() { q(save = "no") tkdestroy(tt) } ) tkgrid(tklabel(tt,text="Put your variables.."),columnspan=3, pady = 10) tkgrid(tklabel(tt,text="x variable"), x.entry, pady= 10, padx= 10) tkgrid(tklabel(tt,text="y variable"), y.entry, pady= 10, padx= 10) tkgrid(tklabel(tt,text="z variable"), z.entry, pady= 10, padx= 10) tkgrid(submit.but, reset.but, quit.but, pady= 10, padx= 10) } mydialog()

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