r - 在R中带有警告的函数中抑制，记录和返回值

Question

有一个带有警告的函数，但它不会影响最终输出。我想将警告捕获到日志中，在控制台上取消显示警告消息并返回该值。

fn1 <- function() {
    warning("this is a warning!")
    return(1)
}

我尝试了withCallingHandlers，但是警告消息仍然打印出来，并且tryCatch阻止了返回值。例如，我使用message假装保存到日志。

withCallingHandlers(expr = fn1(),
                    warning = function(w) {
                        message(paste0("saved to a file: ", w$message))
                        # write(w$message, "xxlocation")
                    }
)

输出

saved to a file: this is a warning!
[1] 1
Warning message:
In fn1() : this is a warning!

我可以使用重新启动来抑制警告，但是我的返回值也被抑制。与tryCatch非常相似:

withCallingHandlers(
    withRestarts(fn1(),
                 mufflewarn=function(msg) {
                     message(msg)
                 }),
    warning = function(w) {
        invokeRestart("mufflewarn", w$message)
    }
)

this is a warning!

有什么办法可以让我输出:

saved to a file: this is a warning!
[1] 1

Answer 1

事实证明，解决方案非常简单，只需使用suppressWarnings就能解决问题:

suppressWarnings(withCallingHandlers(expr = fn1(),
                    warning = function(w) {
                        message(paste0("saved to a file: ", w$message))
                        # write(w$message, "xxlocation")
                    },
                    finally = function(x) suppressWarnings(x)
))

saved to a file: this is a warning!
[1] 1