How to get a screenshot directly into a variable when using R - r

I use R and the Magick package to process screenshots! Currently, I'm going through an external tool to get my screenshots. This tool gives me a file (png or other) that I have to reload to use it with Magick. Is there a package that would allow me to take screenshots (in whole or only partially) and to retrieve the image directly into a variable without going through an intermediate file? I found plenty of stuff for web-snapshots but nothing for a capture of my screen...
Thanks in advance

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RDCOMClient log file

I have been using RDCOMClient for a while now to interact with vendor software. For the most part it has worked fine. Recently, however, I have the need to loop through many operations (several hundred). I am running into problems with the RDCOM.err file growing to a very large size (easily GBs). This file is put in C: with no apparent option to change that. Is there some way that I can suppress this output or specify another location for the file to go? I don't need any of the output in the file so suppressing it would be best.
EDIT: I tried to add to my script a file.remove but R has the file locked. The only way I can get the lock released is to restart R.
Thanks.
Setting the permissions to read only was going to be my suggested hack.
A slightly more elegant approach is to edit one line of the C code in the package in src/RUtils.h from
\#define errorLog(a,...) fprintf(getErrorFILE(), a, ##__VA_ARGS__); fflush(getErrorFILE());
to
\#define errorLog(a, ...) {}
However, I've pushed some simple updates to the package on github that add a writeErrors() function that one can use to toggle whether errors are written or not. So this allows this to be turned on and off dynamically.
So
library(RDCOMClient)
writeErrors(FALSE)
will turn off the error logging to the file.
I found a work around for this. I created the files C:\RDCOM.err and C:\RDCOM_server.err and marked them both as read-only. I am not sure if there is a better way to accomplish this, but for now I am running without logging.

LDAvis HTML output from serVis is blank

I'm trying to use LDAvis for the first time, but have run into the following issue:
After running serVis on my JSON object,
serVis(json, out.dir = 'LDAvis', open.browser = FALSE)
the 5 expected files are created (i.e., d3.v3.js, index.html, lda.css, lda.json, and ldavis.js). As I understand LDAvis, opening the html file should open the interactive viewer. However, in doing this, only a blank webpage is opened.
I've compared the html source code with that from LDAvis projects found online, and they are the same. This was built using Christopher Gandrud's script found here where the LDA results come from the topicmodels package and used the Gibbs method. The underlying data uses ~45K documents with ~15K unique terms. For what it's worth, the lda.json file seems a bit small at ~6MB.
Unfortunately, this issue seems too large to provide sample data or reproducible code. (If I could isolate the issue more, then perhaps I could add sample code.) Instead, I was hoping if readers had any ideas for the cause of this issue or if it has come about before.
Thanks ahead for any feedback!
I've resolved the issue after realizing that most web browsers restrict access to local files. For Chrome, the .exe needs to be called with the option "--allow-file-access-from-files". Otherwise, no error is displayed opening the LDAvis output unless you inspect HTML elements manually.

How to keep modified/downloaded package

R noobie here.
I'm am trying to use a package that I download off of github using source_gist, but it appears that I need to re-download it every time I quit R (I'm using RStudio).
To clarify, the function that I'm using is part of plotrix package and is called barp. Someone made a modified version of it (called barp2) and put it up on github. That's what I want to use.
So my question is this: is there anyway to have this modified code saved inside the plotrix package, so I wouldn't have to download it every time?
I hope I'm explaining this correctly.
So, let's get some quick terminology straight: the function you're getting off of github isn't a package, it's just a single function. If it was a package, you could use devtools::install_github once and then load it with require() or library() like any other package.
A good solution isn't too different. Just go to the gist, copy the code, paste it into your R editor, and save it somewhere as a .R script file. Something like C:/path/to/barp2.R (adjusting, of course, based on where you actually want to keep it and based on your OS). Then you can read it locally using source("C:/path/to/barp2.R") instead of devtools::source_gist().
If you always want to load it, you could load plotrix and then source this file every time R starts with a couple lines in your R profile, see ?Startup as #BondedDust suggests for details on this.
Reading it off of github every time does have the advantage that, if the author fixes bugs or otherwise improves it, you'll always be using the up-to-date version. It has several disadvantages too: requiring an internet connection, losing access if the gist is deleted, or being unable to access old versions if the author changes it in a way you don't like. Keeping a copy of a version you like is a smart move.

Using glmm_funs.R?

I am fitting a GLMM and I had seen some examples where is used the function: overdisp_fun, deļ¬ned in glmm_funs.R, but I don't know which package contain them or how can I call it from R, can somebody help me?
Thanks,
If you google for glmm_funs.R, you'll find links to the script (eg here: http://glmm.wdfiles.com/local--files/trondheim/glmm_funs.R).
You can save the file on your local machine, then call it in your R session with source("path to file/glmm_funs.R").
You will then be able to use the functions contained in the script, including overdisp_fun().
You can think of it a little bit like loading a package, except the functions are just presented in a script.

R2PPT crashes R; are there alternatives to R2PPT?

I am attempting to automate the insertion of JPEG images into Powerpoint. I have a macro done for that already, except using R would be infinitely better for my purposes.
The package R2PPT should do this, I understand. However, I cannot use it. For example, when I try to use PPT.Open, I understand I can do it two different ways by calling method = "rcom" or method = "RDCOMClient". Using the latter, R will always crash, sending an error report to windows. Using the former, it tells me I need to install statconnDCOM , before giving the error:
Error in PPT.Open(x) : attempt to apply non-function.
I cannot install statconnDCOM freely, as I wouldn't call this work non-commercial. So if there isn't a way to get around this issue, are there at least some free alternatives to R2PPT so that I can save several hours of manual work with a simple R code? If there is a way for me to use R2PPT, that would be ideal.
Thanks!
Edit:
I'm using R version 2.15 and downloaded the most recent version of R2PPT. Powerpoint is 2007.
Do you have administrative privileges on this machine?
There is an issue with package RDCOMClient. It needs permissions to write file rdcom.err in the root of drive C:. If you don't have privileges to write to c:, there is a rather cumbersome workaround:
Close R
Create "c:\temp" folder if it doesn't exist.
Locate on your hard drive file rdcomclient.dll. It usually placed in \R\library\RDCOMClient\libs\i386\ and in \R\library\RDCOMClient\libs\x64\ (you need to patch file which corresponds your Windows version - 32 bit or 64 bit). It's recommended to make backup copy of this files before patching.
Open rdcomclient.dll in text editor (Notepad++, for example -http://notepad-plus-plus.org/)
Find in file string c:\rdcom.err - it occurs only once.
Go into overwrite mode (usually by pressing "Ins" key). It is very important that new path will have the same number of characters as original one. Type C:\temp\e.rr instead of c:\rdcom.err
Save the file.
Now all should work fine.
Arguably not an answer, but have you looked at using Sweave/knitr to render your presentations in LaTeX using something like Beamer? (As discussed on slide 17 here.)
Wouldn't help any with getting JPGs into a PowerPoint, but would certainly make putting R-output (numerical or graphical) into a presentation much easier!
Edit: if you want to use knitr (which I recommend), here's another reference.

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