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warnings()在函数中不起作用?怎么能解决这个问题呢?

error-handling r

Alex Holcombe · 技术社区 · 14 年前

op <- options(warn=0)  #although doesn't work for any value of warn
assign("last.warning", NULL, envir = baseenv())  
thisDoesntWork<- function() {
warning("HEY, this is definitely a warning!")
cat(paste("number of warnings:",length(warnings())))
}   
>thisDoesntWork()
Warning in thisDoesntWork() : HEY, this is definitely a warning!
number of warnings: 0

警告数应为1而不是0- 看来 warnings() 如果在函数中调用,则不返回任何内容。为什么?如何解决这个问题,以检查函数中是否出现警告,并将其打印出来?

tryCatch ,因为这样我就失去了函数返回的值(它可能仍然返回有效值,即使它生成了警告)。

5 回复 | 直到 14 年前

Richie Cotton Joris Meys 14 年前

这是密码 suppressWarnings

function (expr) 
{
    withCallingHandlers(expr, warning = function(w) invokeRestart("muffleWarning"))
}

我做了一些调整来计算警告的数量。

countWarnings <- function(expr) 
{
    .number_of_warnings <- 0L
    frame_number <- sys.nframe()
    ans <- withCallingHandlers(expr, warning = function(w) 
    {
      assign(".number_of_warnings", .number_of_warnings + 1L, 
        envir = sys.frame(frame_number))
      invokeRestart("muffleWarning")
    })
    message(paste("No. of warnings thrown:", .number_of_warnings))
    ans
}

测试:

countWarnings(log(-1))
No. of warnings thrown: 1
[1] NaN

foo <- function()
{
  warning("first warning!")
  warning("second warning!")
  warning("third warning!")
  invisible()
}
countWarnings(foo())
No. of warnings thrown: 3
NULL

Joshua Ulrich 14 年前

你的例子做返回警告。

> assign("last.warning", NULL, envir = baseenv())  
> thisDoesntWork <- function() {
+   warning("HEY, this is definitely a warning!")
+   cat(paste("number of warnings:",length(warnings())),"\n")
+ }
> thisDoesntWork()
number of warnings: 0 
Warning message:
In thisDoesntWork() : HEY, this is definitely a warning!
> warnings()  # HEY, here's your warning!!!
Warning message:
In thisDoesntWork() : HEY, this is definitely a warning!

文件不明确,但我不认为 last.warning 获取设置,直到调用完成(特别是考虑到调用是可返回内容的一部分)。

kohske 14 年前

fw<-function(){warning("warn...");return(99)}
fn<-function(){return(88)}

f<-function(){
    w<-0
    v<-NULL
    v<-tryCatch(fw(),warning=function(w){w})
    if("warning"%in%class(v)){
        w<-w+1 # e.g., count up the number of warning
        v<-fw()
    }
    print(v)

    v<-NULL
    v<-tryCatch(fn(),warning=function(w){w})
    if("warning"%in%class(v)){
        w<-w+1 # e.g., count up the number of warning
        v<-fn()
    }
    print(v)
}
f()

如果出现警告,则调用函数两次。。。

VitoshKa 14 年前

这是一个解决办法

..my_warning <- 0L

thisDoesWork<- function(){
    assign("last.warning", NULL, envir = baseenv())  
    warning("HEY, this is definitely a warning!", {..my_warning <<- ..my_warning+1L;""})
    str(last.warning)
    cat(paste("number of warnings:", ..my_warning, "\n"))
}


thisDoesWork()
Warning in thisDoesWork() : HEY, this is definitely a warning!
NULL
number of warnings: 1 
>     thisDoesWork()
Warning in thisDoesWork() : HEY, this is definitely a warning!
NULL
number of warnings: 2 
>     thisDoesWork()
Warning in thisDoesWork() : HEY, this is definitely a warning!
NULL
number of warnings: 3 
>

VitoshKa 14 年前

在函数返回之前不会发出警告。有关选项(“warn”),请参阅文档:

options(warn=1L)
thisDoesntWork()
#Warning in thisDoesntWork() : HEY, this is definitely a warning!
#number of warnings: 1