[Rd] Feature request: txtProgressBar with ability to write to arbitrary stream

[Andreas Borg]

Hi all,

I use txtProgressBar to monitor progress of large computations. What I 
miss is the ability to redirect the progress bar to a stream other than 
stdout, specifically to the message stream. This would be useful for 
running Sweave scripts: When redirected to stderr, the bar could be 
visible even though console output is diverted to the output file (and 
there would be no cluttering of the generated latex).

I'd suggest the following changes to txtProgressBar:
- a new argument 'file' (compare to 'cat') which defaults to stderr() 
(there might be reasons to use stdout(), but I believe a progress bar is 
mostly intended as a diagnostic tool and not for console output, which 
is printed or saved in some cases).
- the calls to 'cat' that update the progress bar get 'file = file' as 
additional argument so that output is redirected as desired.

In case anyone from the core team is willing to incorparate this idea, I 
attached the patch file for the necessary changes below.

Best regards,

Andreas

3c3
<              width = NA, title, label, style = 1)
---
 >              width = NA, title, label, style = 1, file=stderr())
23c23
<             cat(paste(rep.int(char, nb-.nb), collapse=""))
---
 >             cat(paste(rep.int(char, nb-.nb), collapse=""), file = file)
27c27
<                 "\r", paste(rep.int(char, nb), collapse=""), sep = "")
---
 >                 "\r", paste(rep.int(char, nb), collapse=""), sep = 
"", file = file)
38c38
<             cat("\r", paste(rep.int(char, nb), collapse=""), sep = "")
---
 >             cat("\r", paste(rep.int(char, nb), collapse=""), sep = 
"", file = file)
42c42
<                 "\r", paste(rep.int(char, nb), collapse=""), sep = "")
---
 >                 "\r", paste(rep.int(char, nb), collapse=""), sep = 
"", file = file)
54c54
<         cat(paste(c("\r  |", rep.int(" ", nw*width+6)), collapse=""))
---
 >         cat(paste(c("\r  |", rep.int(" ", nw*width+6)), collapse=""), 
file = file)
59c59
<                     ), collapse=""))
---
 >                     ), collapse=""), file = file)
68c68
<             cat("\n")
---
 >             cat("\n", file = file)

-- 
Andreas Borg
Medizinische Informatik

UNIVERSITÄTSMEDIZIN
der Johannes Gutenberg-Universität
Institut für Medizinische Biometrie, Epidemiologie und Informatik
Obere Zahlbacher Straße 69, 55131 Mainz
www.imbei.uni-mainz.de

Telefon +49 (0) 6131 175062
E-Mail: borg at imbei.uni-mainz.de

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