R: Display progression of a long calculation on the console...

progress {svMisc} | R Documentation

## Display progression of a long calculation on the console and/or in a GUI

### Description

Display progression level of a long-running task in the console. Two mode can be used: either percent of achievement (55%), or the number of items or steps done on a total (1 file on 10 done...). This is displayed either through a message, or through a text-based "progression bar" on the console, or a true progression bar widget in a GUI.

### Usage

    progress(value, max.value = NULL, progress.bar = FALSE, char = "|",
        init = (value == 0), console = TRUE, gui = TRUE)

### Arguments

`value` | current value of the progression (use a value higher than `max.value` to dismiss the progression indication automatically.
`max.value` | maximum value to be achieved.
`progress.bar` | should we display a progression bar on the console? If `FALSE`, a temporary message is used.
`char` | the character to use to fill the progress bar in the console. not used for the alternate display, or for GUI display of progression.
`init` | do we have to initialize the progress bar? It is usually done the first time the function is used, and the default value `init = (value == 0)` is correct most of the time. You must specify `init = TRUE` in two cases: (1) if the first value to display is different from zero, and (2) if your code issues some text on screen during progression display. Hence, you must force redraw of the progression bar.
`console` | do we display progression on the console?
`gui` | do we display progression in a dialog box, or any other GUI widget? See "details" and "examples" hereunder to know how to implement your own GUI progression indicator.

### Details

The function `progress()` proposes different styles of pregression indicators than the standard `txtProgressBar` in package 'utils'.

The function uses backspace (\8) to erase characters at the console.

With `gui = TRUE`, the function looks for all functions defined in the '.progress' list located in `SciViews:TempEnv` environment. Each function is executed in turn with following call: `theGUIfunction(value, max.value)`. You are responsible to create `theGUIfunction()` and to add it as an element in the .progress list in `SciViews:TempEnv`. See also example (5) hereunder.

If your GUI display of the progression offers the possibility to stop calculation (for instance, using a 'Cancel' button), you are responsible to pass this info to your code doing the long calculation and to stop it there. Example (5) shows how to do this.

### Value

This function returns NULL invisibly. It is invoked for its side effects.

### Note

In a GUI, it is preferable to use a non modal dialog box with a progress widget, or to display such a progress widget in the status bar of your main window.

### Author(s)

Philippe Grosjean <phgrosjean@sciviews.org>

### See Also

`batch`

### Examples

    ## 1) A simple progress indicator in percent
    for (i in 0:101) {
    	progress(i)
    	Sys.sleep(0.01)
    	if (i == 101) cat("Done!\n")
    }

    ## 2) A progress indicator with 'x on y'
    for (i in 0:31) {
    	progress(i, 30)
    	Sys.sleep(0.02)
    	if (i == 31) cat("Done!\n")
    }

    ## 3) A progress bar in percent
    for (i in 0:101) {
    	progress(i, progress.bar = TRUE)
    	Sys.sleep(0.01)
    	if (i == 101) cat("Done!\n")
    }

    ## 4) A progress indicator with 'x on y'
    for (i in 0:21) {
    	progress(i, 20, progress.bar = TRUE)
    	Sys.sleep(0.03)
    	if (i == 21) cat("Done!\n")
    }

    ## 5) A progression dialog box with Tcl/Tk
    ## Not run:
    if (require(tcltk)) {
        guiProgress <- function(value, max.value) {
            ## Do we need to destroy the progression dialog box?
            if (value > max.value) {
                try(tkdestroy(getTemp("guiProgressWindow")), silent = TRUE)
                ## Clean temporary variables
                rmTemp(c("guiProgressState", "guiProgressWindow", "guiProgressCancel"))
                ## ...and exit
                return(invisible(FALSE))
            } else if (existsTemp("guiProgressWindow") &&
                !inherits(try(tkwm.deiconify(tt <- getTemp("guiProgressWindow")),
                    silent = TRUE), "try-error")) {
                ## The progression dialog box exists
                ## Focus on it and change progress value
                tkfocus(tt)
                State <- getTemp("guiProgressState")
                tclvalue(State) <- value
            } else {
                ## The progression dialog box must be (re)created
                ## First, make sure there is no remaining "guiProgressStop"
                rmTemp("guiProgressCancel")
                ## Create a Tcl variable to hold current progression state
                State <- tclVar(value)
                assignTemp("guiProgressState", State)
                ## Create the progression dialog box
                tt <- tktoplevel()
                assignTemp("guiProgressWindow", tt)
                tktitle(tt) <- "Waiting..."
                sc <- tkscale(tt, orient = "h", state = "disabled", to = max.value,
                    label = "Progress (
                tkpack(sc)
                but <- tkbutton(tt, text = "Cancel", command = function() {
                    ## Set a flag telling to stop running calculation
                    assignTemp("guiProgressCancel", TRUE) # Content is not important!
                    ## Destroy the window
                    tkdestroy(tt)
                })
                tkpack(but)
            }
            return(invisible(TRUE))
        }
        ## Register it as function to use in progress()
        changeTemp(".progress", "guiProgress", guiProgress, replace.existing = FALSE)
        rm(guiProgress) # Don't need this any more
        ## Test it...
        for (i in 0:101) {
        	progress(i) # Could also set console = FALSE for using the GUI only
        	Sys.sleep(0.05)
        	## The code to stop long calc when user presses "Cancel"
        	if (existsTemp("guiProgressCancel")) {
        	    progress(101, console = FALSE) # Make sure to clean up everything
        	    break
        	}
        	if (i == 101) cat("Done!\n")
        }
        ## Unregister the GUI for progress
        changeTemp(".progress", "guiProgress", NULL)
    }

    ## End(Not run)

[Package svMisc version 0.9-70 Index]