progress bar showing C code's progress

AustinD

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Jan 4, 2016, 4:00:37 PM1/4/16

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Hello,

Thanks in advance for any help. I have a C code that is invoked (via system command) from R code running on Shiny server. The C code takes minutes to do its calculation. I am thinking of having C code regularly write a "count" to a text file and R code reads the text file then convert the info to progress bar. I think if I invoke the C code via "system" with "wait = FALSE", perhaps this will work?

Thanks.

Joe Cheng

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Jan 4, 2016, 4:05:46 PM1/4/16

to AustinD, Shiny - Web Framework for R

Yeah, I think that should work. You might consider using reactiveFileReader to monitor the file.

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AustinD

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Jan 4, 2016, 4:59:05 PM1/4/16

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As usuall, thanks Joe for your prompt reply.

How can I show progress if I compile the C code as shared lib and have R code calling the C function via ".c" or ".call"? I think R (and shiny) won't get control to display progress until C code is done. Wait, but in this case, can I have C code calls R code to display progress?

Thanks again.

Joe Cheng

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Jan 4, 2016, 6:01:42 PM1/4/16

to AustinD, Shiny - Web Framework for R

I usually use Rcpp, not raw C, so I don't know exactly how to call R from C--but I believe eval should do it. I would try to pass a closure from R to C that does the right thing.

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Joe Cheng

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Jan 4, 2016, 6:04:21 PM1/4/16

to AustinD, Shiny - Web Framework for R

(Sorry, hit Send too soon.)

You might be able to just call setProgress from C using eval, actually. That might work.

If all else fails you could break up the C code into multiple discrete functions and have R call them individually.

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