The following code sends output to the console when the expression fails even though the try() argument silent = TRUE.
dd = try(unlist(remDr$findElement("css", "#ctl00_mainA")), silent = TRUE)
suppressMessages() does not suppress the output.
dd = suppressMessages(try(unlist(remDr$findElement("css", "#ctl00_mainA")), silent = TRUE))
try() is used to trap the error Selenium message: Unable to locate element: ......... The code logic works perfectly; the script continues to run as intended.
The message is not an Error that appears in red. The message is in black; the same color that results from print() and cat().
Echo is off. The source code does not print to the console.
I want to suppress the message while retaining the ability to send messages to the console with print() and cat().
Would appreciate any ideas.
Use remDr$findElements() instead with the same arguments. If the element you are looking for doesn't exist it just returns a zero length list which is easy to test for, and you don't get a lengthy error message printed to the console.
Related
I am running a simulation study in R. Occassionally, my simulation study produces an error message. As I implemented my simulation study in a function, the simulation stops when this error message occurs. I know that it is bad practice to suppress errors, but at this moment to me there is no other option than to suppress the error and then go on with the next simulation until the total number of simulations I like to run. To do this, I have to suppress the error message R produces.
To do this, I tried different things:
library(base64)
suppressWarnings
suppressMessages
options(error = expression(NULL))
In the first two options, only warnings and message are suprressed, so that's no help. If I understand it correctly, in the last case, all error messages should be avoided. However, that does not help, the function still stops with an error message.
Has someone any idea why this does not work the way I expect it to work? I searched the internet for solutions, but could only find the above mentioned ways.
In the function I am running my simulation, a part of the code is analysed by the external program JAGS (Gibbs sampler) and the error message is produced by this analysis. Might this be where it goes wrong?
Note that I do not have to supress a certain/specific error message, as there are no other error messages produced, it is 'good enough' to have an option that supresses just all error messages.
Thanks for your time and help!
As suggested by the previous solution, you can use try or tryCatch functions, which will encapsulate the error (more info in Advanced R). However, they will not suppress the error reporting message to stderr by default.
This can be achieved by setting their parameters. For try, set silent=TRUE. For tryCatch set error=function(e){}.
Examples:
o <- try(1 + "a")
> Error in 1 + "a" : non-numeric argument to binary operator
o <- try(1 + "a", silent=TRUE) # no error printed
o <- tryCatch(1 + "a")
> Error in 1 + "a" : non-numeric argument to binary operator
o <- tryCatch(1 + "a", error=function(e){})
There is a big difference between suppressing a message and suppressing the response to an error. If a function cannot complete its task, it will of necessity return an error (although some functions have a command-line argument to take some other action in case of error). What you need, as Zoonekynd suggested, is to use try or trycatch to "encapsulate" the error so that your main program flow can continue even when the function fails.
I am using the function FixedPoint() from the package FixedPoint for some computations in R. Even if a fixed point of some function cannot be found, FixedPoint() still returns output (indicating the error) and, in addition, returns an error message. I want to suppress any such additional error messages from being printed. Neither try(), nor suppressWarnings(), nor suppressMessages() seem to work. Please find an example below that produces such an additional error message.
library(FixedPoint)
ell=0.95
delta=0.1
r=0.1
lambda=1
tH=1
tL=0.5
etaL=1
etaH=1
sys1=function(y){
A=y[1]
B=y[2]
TA=(etaM*(1-exp(-(lambda*A+lambda*(A+B)+2*delta)*tL))-2*lambda*A^2-lambda*A*B)/2/delta
TB=(etaM*exp(-(lambda*A+lambda*(A+B)+2*delta)*tL)*(1-exp(-(lambda*(A+B)+2*delta)*(tH-tL)))-lambda*B^2-lambda*A*B)/2/delta
return(c(TA,TB))
}
FixedPoint(sys1,c(1.90,0.04))
This seems to work:
cc <- capture.output(ff <- FixedPoint(sys1,c(1.90,0.04)),type="message")
where ff now holds the output you want. (Alternately, you could wrap capture.output(...) in invisible() rather than assigning its return value to a variable.)
The problem seems to be that the error message emanates from an un-silence-d try() clause within the package code.
When I use rmarkdown::render to compile the following code into html,
```{r, error=T}
setClass('A', slots=c())
try(setClass('A', slots=c()))
```
I found that there is no error message shown in the html file for the second command, instead it is printed in the command line. Does anybody know to make the error message printed in the html file as well? Thanks.
here are 2 methods to print the error message
```{r, error=T}
setClass('A', slots=c())
#method 1
temp <- try(setClass('A', slots=c()))
message(temp)
#method 2
try(setClass('A', slots=c()))
message(geterrmessage())
```
found the 2 methods from Details section in ?try
try evaluates an expression and traps any errors that occur during the
evaluation. If an error occurs then the error message is printed to
the stderr connection unless options("show.error.messages") is false
or the call includes silent = TRUE. The error message is also stored
in a buffer where it can be retrieved by geterrmessage. (This should
not be needed as the value returned in case of an error contains the
error message.)
So I am using a function in R that uses compiled fortran code. While using this function, lsoda, in package deSolve. I get messages printed to the screen like
DLSODA- At current T (=R1), MXSTEP (=I1) steps
taken on this call before reaching TOUT
In above message, I =
[1] 5000
In above message, R =
[1] 21.31629
The problem is that the above is not a "warning" or an "error"; the is.null(warnings()) evaluates to TRUE after I see this message. If it were a warning I could just write x = is.null(warnings()) and that would do the trick. I could use tryCatch for errors, but what about messages that are neither errors or warnings?
The reason I ask, is that this function is called in a while loop, inside a for loop. I want the while loop to break if this message gets printed, and then for the outer for loop to move onto the next iteration. Normally you'd use tryCatch to do something like this but because there is no error, I have no idea how to do this
You can redirect the output and then check whether lsoda printed something:
out <- capture.output(lsoda(...))
if(length(grep("In above message", out))!=0) {
# error
}
We basically check whether any of the lines printed by lsoda contains the string In above message. If you need to use the result from lsoda, you can also run like this:
out <- capture.output(result <- lsoda(...))
As suggested, you can also use grepl:
if(any(grepl("In above message", out))) {
# error
}
I'm facing a strange issue in R.
Consider the following code (a really simplified version of the real code but still having the problem) :
library(timeSeries)
tryCatch(
{
specificWeekDay <- 2
currTs <- timeSeries(c(1,2),c('2012-01-01','2012-01-02'),
format='%Y-%m-%d',units='A')
# just 2 dates out of range
start <- time(currTs)[2]+100*24*3600
end <- time(currTs)[2]+110*24*3600
# this line returns an empty timeSeries
currTs <- window(currTs,start=start,end=end)
message("Up to now, everything is OK")
# this is the line with the uncatchable error
currTs[!(as.POSIXlt(time(currTs))$wday %in% specificWeekDay),] <- NA
message("I'm after the bugged line !")
},error=function(e){message(e)})
message("End")
When I run that code in RGui, I correctly get the following output:
Up to now, everything is OK
error in evaluating the argument 'i' in
selecting a method for function '[<-': Error in
as.POSIXlt.numeric(time(currTs)) : 'origin' must be supplied
End
Instead, when I run it through RScript (in windows) using the following line:
RScript.exe --vanilla "myscript.R"
I get this output:
Up to now, everything is OK
Execution interrupted
It seems like RScript crashes...
Any idea about the reason?
Is this a timeSeries package bug, or I'm doing something wrong ?
If the latter, what's the right way to be sure to catch all the errors ?
Thanks in advance.
EDIT :
Here's a smaller example reproducing the issue that doesn't use timeSeries package. To test it, just run it as described above:
library(methods)
# define a generic function
setGeneric("foo",
function(x, ...){standardGeneric("foo")})
# set a method for the generic function
setMethod("foo", signature("character"),
function(x) {x})
tryCatch(
{
foo("abc")
foo(notExisting)
},error=function(e)print(e))
It seems something related to generic method dispatching; when an argument of a method causes an error, the dispatcher cannot find the signature of the method and conseguently raises an exception that tryCatch function seems unable to handle when run through RScript.
Strangely, it doesn't happen for example with print(notExisting); in that case the exception is correctly handled.
Any idea about the reason and how to catch this kind of errors ?
Note:
I'm using R-2.14.2 on Windows 7
The issue is in the way the internal C code implementing S4 method dispatch tries to catch and handle some errors and how the non-interactive case is treated in this approach. A work-around should be in place in R-devel and R-patched soon.
Work-around now committed to R-devel and R-patched.
Information about tryCatch() [that the OP already knew and used but I didn't notice]
I think you are missing that your tryCatch() is not doing anything special with the error, hence you are raising an error in the normal fashion. In interactive use the error is thrown and handled in the usual fashion, but an error inside a script run in a non-interactive session (a la Rscript) will abort the running script.
tryCatch() is a complex function that allows the potential to trap and handle all sorts of events in R, not just errors. However by default it is set up to mimic the standard R error handling procedure; basically allow the error to be thrown and reported by R. If you want R to do anything other than the basic behaviour then you need to add a specific handler for the error:
> e <- simpleError("test error")
> tryCatch(foo, error = function(e) e,
+ finally = writeLines("There was a problem!"))
There was a problem!
<simpleError in doTryCatch(return(expr), name, parentenv, handler): object 'foo'
not found>
I suggest you read ?tryCatch in more detail to understand better what it does.
An alternative is to use try(). To modify your script I would just do:
# this is the line with the uncatchable error
tried <- try(currTs[!(as.POSIXlt(time(currTs))$wday %in% specificWeekDay),] <- NA,
silent = TRUE)
if(inherits(tried, "try-error")) {
writeLines("There was an error!")
} else {
writeLines("Everything worked fine!")
}
The key bit is to save the object returned from try() so you can test the class, and to have try() operate silently. Consider the difference:
> bar <- try(foo)
Error in try(foo) : object 'foo' not found
> bar <- try(foo, silent = TRUE)
> class(bar)
[1] "try-error"
Note that in the first call above, the error is caught and reported as a message. In the second, it is not reported. In both cases an object of class "try-error" is returned.
Internally, try() is written as a single call to tryCatch() which sets up a custom function for the error handler which reports the error as a message and sets up the returned object. You might wish to study the R code for try() as another example of using tryCatch().