progress: 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.

Value

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

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.

Examples

Run this code

## 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)