I'm completely new to Shiny and I can't get a textOutput to render when I want it to.
observeEvent(input$btnPersistencia, {
output$txtProtActual <- renderText("PROCESSING...")
print("This does print in console")
#SomeCodeHere that takes about 10 seconds to finish
output$txtProtActual <- renderText(paste("Archivo Persistencia Actual: ", basename(values$file), "\n Dim: ", isolate(input$sliderDimension), "\n Filtr: ", isolate(input$txtMaxFil)))
})
The text isn't showing "Processing..." while #SomeCodeHere is running. I really don't understand why. Shouldn't it work?
The text is only rendered AFTER the observeEvent is finished. I know this because if I remove the SECOND renderText(), the text takes the value "Processing..." when the processing is over.
If this is the normal behaviour, is there a way to force the render before the observeEvent is over?
EDIT:
Is there another (any) way to achieve what I want?
Posting my comment as an answer (thanks!)
The article about Progress Bars is here and the reference here.
Here's your code with the progress bar:
observeEvent(input$btnPersistencia, {
withProgress(message = 'PROCESSING...', value = 0, {
incProgress(1/2)
#SomeCodeHere that takes about 10 seconds to finish
Sys.sleep(10)
})
output$txtProtActual <- renderText({
paste("Archivo Persistencia Actual: ", basename(values$file),
"\n Dim: ", isolate(input$sliderDimension),
"\n Filtr: ", isolate(input$txtMaxFil)
)
})
})
Although it's not related to your question, I've noticed you've placed an output inside an observeEvent with some isolate wrapping inputs.
One of the shiny developers talks about observers in the first two videos of shiny's 2016 conference. It helped me understand a lot better how to use observers and I thought you might find it useful. :]
Related
I have a long running process, coded in "R". I would like to continue running it in RStudio, I don't want to use batch mode.
I would like to allow the user to gracefully terminate the long running process, for example by pressing the escape key. If the user doesn't press anything, the process continues, without waiting.
I have read other StackOverflow posts, perhaps I need to prompt the user using scan/readline on a different thread. That way, the main execution thread isn't blocked.
Isn't there a simpler way?
Thank you for any pointers/suggestions.
Richard Rogers
Further comments:
I've made a few mistakes:
I didn't realize that pressing escape in RStudio while the code is
running halts execution.
I can't seem to determine where execution ends when I press escape.
Maybe I can use a simpler question.
Here is a simple function:
ProcessData <- function()
{
Continue <- TRUE
Iteration <- 1
TestData <- vector(mode = "integer", length = 100000)
while (Continue)
{
writeLines(sprintf("Processing iteration %d, Current time is %s", Iteration, Sys.time()))
process.events()
TestData <- round(runif(100000, min = 1, max = 10))
# Continue <- PromptUser()
Iteration <- Iteration + 1
}
writeLines("Processing ending.")
head(TestData)
}
If I press escape while the loop is running, the writeLines and head calls don't get executed. How can I ensure that they do?
Thank you again,
Richard
I know this is an old question, but since I had a similar context (long-running task), here is what I came up with:
long_computation <- function() for(i in 1:10) Sys.sleep(1)
exit_gracefully <- function() cat("Saving results so far...\n")
tryCatch(
long_computation(),
finally = exit_gracefully()
)
If we press escape during the computation, no error condition seems to be thrown; however the finally part of tryCatch gets executed. This allows us to clean up, close connections etc.
I am writing up some data processing stuff and I wanted to have a concise progress status printing a fraction that updates over time on a single line in the console.
To get this done I wanted to have something like this
print(Initiating data processing...)
for(sample in 1:length(data)){
print(paste(sample,length(data),sep="/"))
process(data[[sample]])
#Unprint the bottom line in the console ... !!! ... !!!.. ?
}
Keeping the screen clean and what not. I don't quite know how to do it. I know that there is a R text progress bar but for utilities sake I'm looking for a little more control.
Thanks!
I think your best bet is to do exactly what the R text progress bar does, which is "\r to return to the left margin", as seen in the help file. You'll have to use cat instead of print because print ends with a newline.
cat("Initiating data processing...\n")
for(sample in 1:length(data)){
cat(sample, length(data), sep="/")
process(data[[sample]])
cat("\r")
}
cat("\n")
I have looked at other posts that appeared similar to this question but they have not helped me. This may be just my ignorance of R. Thus I decided to sign up and make my first post on stack-overflow.
I am running an R-script and would like the user to decide either to use one of the two following loops. The code to decide user input looks similar to the one below:
#Define the function
method.choice<-function() {
Method.to.use<-readline("Please enter 'New' for new method and'Old' for old method: ")
while(Method.to.use!="New" && Method.to.use!="Old"){ #Make sure selection is one of two inputs
cat("You have not entered a valid input, try again", "\n")
Method.to.use<-readline("Please enter 'New' for new method and 'Old' for old method: ")
cat("You have selected", Method.to.use, "\n")
}
return(Method.to.use)
}
#Run the function
method.choice()
Then below this I have the two possible choices:
if(Method.to.use=="New") {
for(i in 1:nrow(linelist)){...}
}
if(Method.to.use=="Old"){
for(i in 1:nrow(linelist)){...}
}
My issue is, and what I have read from other posts, is that whether I use "readline", "scan" or "ask", R does not wait for my input. Instead R will use the following lines as the input.
The only way I found that R would pause for input is if the code is all on the same line or if it is run line by line (instead of selecting all the code at once). See example from gtools using "ask":
silly <- function()
{
age <- ask("How old are you? ")
age <- as.numeric(age)
cat("In 10 years you will be", age+10, "years old!\n")
}
This runs with a pause:
silly(); paste("this is quite silly")
This does not wait for input:
silly()
paste("this is quite silly")
Any guidance would be appreciated to ensure I can still run my entire script and have it pause at readline without continuing. I am using R-studio and I have checked that interactive==TRUE.
The only other work-around I found is wrapping my entire script into one main function, which is not ideal for me. This may require me to use <<- to write to my environment.
Thank you in advance.
I am searching for a way to get user input inside a loop while executing in batch mode.
readLines() and scan() work well for me in interactive mode only, in batch mode they start to read in lines of code as user input, unless all the code is surrounded by {}, which is inconvenient. I need a simple solution to get just 1 integer value in a way that I can just type in value and press ENTER, so
the input field (if the solution involves GUI) must automatically get focus and
ENTER must trigger end of input/submission.
I can't find a way to do it that will satisfy both conditions, e.g. ginput() from gWidgets activates the input field, but ENTER doesn't trigger form submission.
Here is how I solved my own problem:
require(gWidgets)
options(guiToolkit="RGtk2")
INPUT <- function(message) {
CHOICE <- NA
w <- gbasicdialog(title=message, handler = function(h,...) CHOICE <<- svalue(input))
input <- gedit("", initial.msg="", cont=w, width=10)
addHandlerChanged(input, handler=function (h, ...) {
CHOICE <<- svalue(input)
dispose(w)
})
visible(w, set=TRUE)
return(CHOICE)
}
repeat{
x=INPUT("Input an integer")
if(!is.na(as.integer(x))) break
}
print(x)
Update:
I can't test this right now, but take a look at ?menu and have it pop up a gui window.
I'm not certain if that will work, but it is different in that it takes a mouse-click response.
original answer:
As per the documentation to ?readline:
This can only be used in an interactive session.
..
In non-interactive use the result is as if the response was RETURN and the value is "".
If you are simply waiting for one piece of information, and you do not know this piece of information before beginning the execution of the script (presumably, there is a decision to be made which is dependent on the results earlier in the script), then one alternative is to simply break your script up into three parts:
everything before the decision point.
an interactive script which prompts for input
everything after the decision point.
And simply chain the three together by having the first end by calling the second in an interactive session. Then have the second end by calling the third.
I (sort of) already know the answer to this question. But I figured it is one that gets asked so frequently on the R Users list, that there should be one solid good answer. To the best of my knowledge there is no multiline comment functionality in R. So, does anyone have any good workarounds?
While quite a bit of work in R usually involves interactive sessions (which casts doubt on the need for multiline comments), there are times when I've had to send scripts to colleagues and classmates, much of which involves nontrivial blocks of code. And for people coming from other languages it is a fairly natural question.
In the past I've used quotes. Since strings support linebreaks, running an R script with
"
Here's my multiline comment.
"
a <- 10
rocknroll.lm <- lm(blah blah blah)
...
works fine. Does anyone have a better solution?
You can do this easily in RStudio:
select the code and click CTR+SHIFT+C
to comment/uncomment code.
This does come up on the mailing list fairly regularly, see for example this recent thread on r-help. The consensus answer usually is the one shown above: that given that the language has no direct support, you have to either
work with an editor that has region-to-comment commands, and most advanced R editors do
use the if (FALSE) constructs suggested earlier but note that it still requires complete parsing and must hence be syntactically correct
A neat trick for RStudio I've just discovered is to use #' as this creates an self-expanding comment section (when you return to new line from such a line or insert new lines into such a section it is automatically comment).
[Update] Based on comments.
# An empty function for Comments
Comment <- function(`#Comments`) {invisible()}
#### Comments ####
Comment( `
# Put anything in here except back-ticks.
api_idea <- function() {
return TRUE
}
# Just to show api_idea isn't really there...
print( api_idea )
`)
####
#### Code. ####
foo <- function() {
print( "The above did not evaluate!")
}
foo()
[Original Answer]
Here's another way... check out the pic at the bottom. Cut and paste the code block into RStudio.
Multiline comments that make using an IDE more effective are a "Good Thing", most IDEs or simple editors don't have highlighting of text within simple commented -out blocks; though some authors have taken the time to ensure parsing within here-strings. With R we don't have multi-line comments or here-strings either, but using invisible expressions in RStudio gives all that goodness.
As long as there aren't any backticks in the section desired to be used for a multiline comments, here-strings, or non-executed comment blocks then this might be something worth-while.
#### Intro Notes & Comments ####
invisible( expression( `
{ <= put the brace here to reset the auto indenting...
Base <- function()
{ <^~~~~~~~~~~~~~~~ Use the function as a header and nesting marker for the comments
that show up in the jump-menu.
--->8---
}
External <- function()
{
If we used a function similar to:
api_idea <- function() {
some_api_example <- function( nested ) {
stopifnot( some required check here )
}
print("Cut and paste this into RStudio to see the code-chunk quick-jump structure.")
return converted object
}
#### Code. ####
^~~~~~~~~~~~~~~~~~~~~~~~~~ <= Notice that this comment section isnt in the jump menu!
Putting an apostrophe in isn't causes RStudio to parse as text
and needs to be matched prior to nested structure working again.
api_idea2 <- function() {
} # That isn't in the jump-menu, but the one below is...
api_idea3 <- function() {
}
}
# Just to show api_idea isn't really there...
print( api_idea )
}`) )
####
#### Code. ####
foo <- function() {
print( "The above did not evaluate and cause an error!")
}
foo()
## [1] "The above did not evaluate and cause an error!"
And here's the pic...
I can think of two options. The first option is to use an editor that allows to block comment and uncomment (eg. Eclipse). The second option is to use an if statement. But that will only allow you to 'comment' correct R syntax. Hence a good editor is the prefered workaround.
if(FALSE){
#everything in this case is not executed
}
If find it incredible that any language would not cater for this.
This is probably the cleanest workaround:
anything="
first comment line
second comment line
"
Apart from using the overkilled way to comment multi-line codes just by installing RStudio, you can use Notepad++ as it supports the syntax highlighting of R
(Select multi-lines) -> Edit -> Comment/Uncomment -> Toggle Block Comment
Note that you need to save the code as a .R source first (highlighted in red)
I use vim to edit the R script.
Let's say the R script is test.R, containing say "Line 1", "Line 2", and "Line 3" on 3 separate lines.
I open test.R on the command line with Vim by typing "vim test.R".
Then I go to the 1st line I want to comment out, type "Control-V", down arrow to the last line I want to comment out, type a capital I i.e. "I" for insert, type "# ", and then hit the Escape key to add "# " to every line that I selected by arrowing down. Save the file in Vim and then exit Vim by typing ":wq". Changes should show up in Rstudio.
To delete the comments in Vim, start at the first line on top of the character "#" you want to delete, again do "Control-V", and arrow down to the last line you want to delete a "#" from. Then type "dd". The "#" signs should be deleted.
There's seconds-worth of lag time between when changes to test.R in Vim are reflected in Rstudio.
Now there is a workaround, by using package ARTofR or bannerCommenter
Examples here:
In RStudio an easy way to do this is to write your comment and once you have used CTRL + Shift + C to comment your line of code, then use CTRL + SHIFT + / to reflow you comment onto multiple lines for ease of reading.
In RStudio you can use a pound sign and quote like this:
#' This is a comment
Now, every time you hit return you don't need to add the #', RStudio will automatically put that in for you.
Incidentally, for adding parameters and items that are returned, for standardization if you type an # symbol inside those comment strings, RStudio will automatically show you a list of codes associated with those comment parameters:
#' #param tracker_df Dataframe of limit names and limits
#' #param invoice_data Dataframe of invoice data
#' #return return_list List of scores for each limit and rejected invoice rows