Useful links/commands
https://github.com/stan-dev/rstan/wiki/Install-Rtools-for-Windows
https://github.com/joshkatz/r-script NodeJS to/from R
https://rstudio.github.io/promises/
https://rstudio.github.io/promises/articles/casestudy.html async
https://community.rstudio.com/t/error-handling-in-shiny-async-promise-future/9454
https://gist.github.com/wch/5436415/ Shiny example app with dynamic number of plots
https://www.datasciencecentral.com/profiles/blogs/dummy-errors-when-using-neuralnet-package-in-r

Debugging
https://shiny.rstudio.com/articles/debugging.html
If you want to actually browse the environment of a stack frame interactively, use recover() to select a frame.
https://support.rstudio.com/hc/en-us/articles/205612627-Debugging-with-RStudio
options(shiny.reactlog=TRUE)
options(encoding = "UTF-8")
sudo gedit shiny-server.conf
sudo service shiny-server restart
try http://127.0.0.1:3838/sample-apps/sampdistclt/

RStudio does not invoke the debugger if it looks like none of your own code is on the stack.
If you find that this is excluding an error you want to catch,
go to Tools -> Global Options and uncheck “Use debug error handler only when my code contains errors”.

Installing missing packages
pkgs <- c("shiny", "dplyr", "treemap", "gridBase")
pkgs_needed <- pkgs[!(pkgs %in% installed.packages()[,"Package"])]
if(length(pkgs_needed)) install.packages(pkgs_needed)

use installr package to upgrade R link
- updateR(TRUE) function which updates R runtime to a new version and also its packages. Ok in R GUI and Rstudio.
- see also function copy.packages.between.libraries
- see also this link

Error: Failed to install 'blotter' from GitHub
(converted from warning) incomplete final line found on 'C:\Users\me\Documents\.Rprofile'
> add empty line at end of .Rprofile

Unwanted warnings in RStudio
When sourcing/executing R code > There were 12 warnings (use warnings() to see them)
> assign("last.warning", NULL, envir = baseenv())
see also diagnostics off in fixing a multiple warning unknown column

Run app from Github repo
shiny::runGitHub('manolo20/shinytreemap')

Deploy on shinyapps.io and others
rsconnect::setAccountInfo(name='urname', token='ttt', secret='xxx')
rsconnect::deployApp('C:/Projects/R/urproj') # must have app.R file

Shiny downloadButton Disable "target='_blank" tag
> https://community.rstudio.com/t/downloadbutton-disable-target-blank-tag/6605

rstudio "error creating notebook: cannot open the connection"
> open a Project

compile library source code link
> open any R-project > Project Options : Build Tools: set the folder where the source files are
> Make (somewhere on right top side of Studio..) > "Build Binary" command > will create ZIP file > install BIN package in Studio
(or Open Project to be built from foldr > Build > tar.gz file - needs Rtools.exe installed on computer

when reloading newly compiled library: "quantmod.rdb is corrupt"
> restart R session

Error in order(order_by)[[n]] : subscript out of bounds  when we run: bt.run(bten, trade.summary=F, silent=TRUE)
Called from: nth(x, -1L, order_by = order_by, default = default)
> nth is namespace:dplyr, called by 'last()' also namespace:dplyr in bt.run which relies on base::last() !

Error in EMA(c(NA, NA, NA, NA, NA,  
> number of non-NA values in column(s) 1 > decrease parameter n or replace NAs with data

Read Excel files
http://www.milanor.net/blog/read-excel-files-from-r/
https://gist.github.com/schaunwheeler/5825002/raw/3526a15b032c06392740e20b6c9a179add2cee49/xlsxToR.r XLSX
wb = xlsxToR("C:\\Users\\user1\\Downloads\\Ten-Symbol-Ten-Years.xlsx",keep_sheets=NULL, header=TRUE)
|++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 47s

'c:/Rtools/mingw_64/bin/g++: not found' cannot compile = wrong folder
> https://github.com/stan-dev/rstan/issues/467
> cat('Sys.setenv(BINPREF = "C:/Util/Rtools/mingw_$(WIN)/bin/")', file = file.path(Sys.getenv("HOME"), ".Rprofile"), sep="\n", append = TRUE)

unable to find an inherited method for function ‘span’ for signature ‘"shiny.tag"’
> was using geosphere::span instead of htmltools::span

# RS-DBI driver: cannot allocate a new connection -- maximum of 16 connections already opened
> lapply(dbListConnections(PostgreSQL()), dbDisconnect)

cannot remove prior installation of package
> stop ALL R sessions > Sys.getenv("R_LIBS_USER") > go to pckgs folder > cmd > del /f filename
C:/Users/user1/Documents/R/win-library/3.5

Warning: Error in [.data.frame: undefined columns selected
> bad data.frame in chart_Series or add_TA

quantstrat applyStrategy 'Transactions must be added in order'
> .blotter <- new.env(); .strategy <- new.env()
object '.blotter' not found
# https://stat.ethz.ch/pipermail/r-sig-finance/2012q2/010169.html
> if (!exists('.blotter')) .blotter <- new.env()

blotter: Warning in getInstrument(Symbol) : instrument BCOR not found, please create it first.
> stock(symbols, currency="USD")

Error in curl::curl_fetch_memory(url, handle = handle) : Recv failure: Connection was reset
> was HTTP, replace by HTTPS

Dygraph
https://stackoverflow.com/questions/55361481/show-hide-series-interractively-in-dygraph?rq=1
> You could do it with a plugin like this one https://github.com/rstudio/dygraphs/issues/63
similar to this http://dygraphs.com/tests/visibility.html

r layout 'invalid graphics state'
> dev.off()

need finite 'ylim' values
> In plot1, change y = range(x$VALUE) to y = range(x$VALUE, na.rm=TRUE) to remove NA missing values.

Error in plot.new() : figure margins too large
> graphics.off()
par("mar") #> [1] 5.1 4.1 4.1 2.1
par(mar=c(1,1,1,1))
"Error in plot.new() : figure margins too large". To avoid such errors you can first check par("mar") output. You should be getting:
[1] 5.1 4.1 4.1 2.1
To change that write:
par(mar=c(1,1,1,1)) This should rectify the error. Or else you can change the values accordingly.

after restart R: Error in plot.xy(xy.coords(x, y), type = type, ...) : plot.new has not been called yet
> plot.new()

Warning: Error in xy.coords: 'x' and 'y' lengths differ
> set Sys.envir(TZ='UTC')

rselenium not resolved from current namespace (subprocess)
> restart R

DOM element attributes in Shiny
https://stackoverflow.com/questions/49668048/get-attribute-of-element-in-rendered-ui-with-javascript-in-shiny

$('html').on('DOMNodeInserted', 'iframe', function() {
  alert("Fire in the hole!");
  # Getting and setting CSS properties
  $(this).css('background');                  # get
  $(this).css('background-color', '#330000'); # set
  # Getting elements attributes
  $(this).attr('frameborder');      # get
  $(this).attr('frameborder', '0'); # set
});