attempt() is a wrapper around base try() that allows you to insert a custom messsage on error.
attempt(log("a"))
#> Error: non-numeric argument to mathematical function
# Error: non-numeric argument to mathematical function
attempt(log("a"), msg = "Nop !")
#> Error: Nop !
# Error: Nop !You can make it verbose (i.e. returning the expression):
attempt(log("a"), msg = "Nop !", verbose = TRUE)
#> Error in log("a"): Nop !
# Error in log("a"): Nop !Of course the result is returned if there is one:
As with try(), the result can be saved as an error object:
a <- attempt(log("a"), msg = "Nop !", verbose = TRUE)
#> Error in log("a"): Nop !
a
#> [1] "Error in log(\"a\"): Nop !\n"
#> attr(,"class")
#> [1] "try-error"
#> attr(,"condition")
#> <simpleError in log("a"): Nop !>
# [1] "Error in log(\"a\"): Nop !\n"
# attr(,"class")
# [1] "try-error"
# attr(,"condition")
# <simpleError in log("a"): Nop !>You can check if the result is an error with is_try_error()
silent_attempt() is a wrapper around silently() (see further down for more info) and attempt(). It attempts to run the expr, stays silent if the expression succeeds, and returns error or warnings if any.
You can write a try catch with these params:
expr the expression to be evaluated.e a mapper or a function evaluated when an error occurs.w a mapper or a function evaluated when a warning occurs.f a mapper or an expression which is always evaluated before returning or exitingIn .e and .f, the .x refers to the error / warning object.
try_catch(expr = log("a"),
.e = ~ paste0("There is an error: ", .x),
.w = ~ paste0("This is a warning: ", .x))
#> [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
#[1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
try_catch(log("a"),
.e = ~ stop(.x),
.w = ~ warning(.x))
#> Error in log("a"): non-numeric argument to mathematical function
# Error in log("a") : non-numeric argument to mathematical function
try_catch(matrix(1:3, nrow= 2),
.e = ~ print(.x),
.w = ~ print(.x))
#> <simpleWarning in matrix(1:3, nrow = 2): data length [3] is not a sub-multiple or multiple of the number of rows [2]>
#<simpleWarning in matrix(1:3, nrow = 2): data length [3] is not a sub-multiple or multiple of the number of rows [2]>
try_catch(expr = 2 + 2 ,
.f = ~ print("Using R for addition... ok I'm out!"))
#> [1] "Using R for addition... ok I'm out!"
#> [1] 4
# [1] "Using R for addition... ok I'm out!"
# [1] 4As usual, the handlers are set only if you call them:
try_catch(matrix(1:3, nrow = 2), .e = ~ print("error"))
#> Warning in matrix(1:3, nrow = 2): data length [3] is not a sub-multiple or
#> multiple of the number of rows [2]
#> [,1] [,2]
#> [1,] 1 3
#> [2,] 2 1
# [,1] [,2]
# [1,] 1 3
# [2,] 2 1
# Warning message:
# In matrix(1:3, nrow = 2) :
# data length [3] is not a sub-multiple or multiple of the number of rows [2]{attempt} is flexible in how you can specify your arguments.
You can, as you do with {base} tryCatch(), use a plain old function:
try_catch(log("a"),
.e = function(e){
print(paste0("There is an error: ", e))
print("Ok, let's save this")
time <- Sys.time()
a <- paste("+ At",time, ", \nError:",e)
# write(a, "log.txt", append = TRUE) # commented to prevent log.txt creation
print(paste("log saved on log.txt at", time))
print("let's move on now")
})
#> [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
#> [1] "Ok, let's save this"
#> [1] "log saved on log.txt at 2019-04-08 08:52:27"
#> [1] "let's move on now"
# [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
# [1] "Ok, let's save this"
# [1] "log saved on log.txt at 2018-01-30 16:59:13"
# [1] "let's move on now"You can even mix both:
try_catch(log("a"),
.e = function(e){
paste0("There is an error: ", e)
},
.f = ~ print("I'm not sure you can do that pal !"))
#> [1] "I'm not sure you can do that pal !"
#> [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
# [1] "I'm not sure you can do that pal !"
# [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
try_catch(log("a"),
.e = ~ paste0("There is an error: ", .x),
.f = function() print("I'm not sure you can do that pal !"))
#> [1] "I'm not sure you can do that pal !"
#> [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"
# [1] "I'm not sure you can do that pal !"
# [1] "There is an error: Error in log(\"a\"): non-numeric argument to mathematical function\n"try_catch_df()try_catch_df() returns a tibble with the call, the error message if any, the warning message if any, and the value of the evaluated expression or “error”. The values will always be contained in a list-column.
res_log <- try_catch_df(log("a"))
res_log
#> call error warning value
#> 1 log("a") non-numeric argument to mathematical function NA error
res_log$value
#> [[1]]
#> [1] "error"
res_matrix <- try_catch_df(matrix(1:3, nrow = 2))
res_matrix
#> call error
#> 1 matrix(1:3, nrow = 2) NA
#> warning
#> 1 data length [3] is not a sub-multiple or multiple of the number of rows [2]
#> value
#> 1 1, 2, 3, 1
res_matrix$value
#> [[1]]
#> [,1] [,2]
#> [1,] 1 3
#> [2,] 2 1
res_success <- try_catch_df(log(1))
res_success
#> call error warning value
#> 1 log(1) NA NA 0
res_success$value
#> [[1]]
#> [1] 0map_try_catch()map_try_catch() and map_try_catch_df() allow you to map on a list of arguments l, to be evaluated by the function in fun.
map_try_catch(l = list(1, 3, "a"), fun = log, .e = ~ .x)
#> [[1]]
#> [1] 0
#>
#> [[2]]
#> [1] 1.098612
#>
#> [[3]]
#> <simpleError in .Primitive("log")("a"): non-numeric argument to mathematical function>
map_try_catch_df(list(1,3,"a"), log)
#> call error
#> 1 .Primitive("log")(1) <NA>
#> 2 .Primitive("log")(3) <NA>
#> 3 .Primitive("log")("a") non-numeric argument to mathematical function
#> warning value
#> 1 NA 0
#> 2 NA 1.098612
#> 3 NA error