问题描述
我试图阅读所有内容，但是我有点陷入一个问题.通过使用bigrquery，我向Google BigQuery创建查询以获取数据-不幸的是，有时由于超时，我的查询无法正常工作.Q是一个SQL查询，BQ应该存储从BigQuery下载的数据.
I tried to read everything, but i kind of got stuck on one problem.By using bigrquery I create queries to Google BigQuery to get data - unfortunately sometimes my query doesn't work because of a time-out.Q is a SQL-Query and BQ is supposed to store the data downloaded from BigQuery.
有人知道每次tryCatch给我一个错误时如何重新做一个循环吗?
Does anybody know how to re-do a loop every time tryCatch gives me an error?
到目前为止，我已经知道了:
I got this so far:
BQ_Foo <- NULL
tryCatch(
{
repeat{
BQ_Foo <- query_exec(Q_foo,"bigquery")
if(is.list(BQ_Foo) == TRUE)break }
}
,error=function(e){cat("ERROR : Query not loaded!", "\n")}
)
我再次尝试了第一种方法，这次我收到以下错误消息:
I tried my first approach again and this time i received this error message:
有人知道如何处理吗?
推荐答案
广泛基于r2evans的答案，这是在withRestarts做同样事情的方法. www.win-vector.com/blog/2012/10/error-handling-in-r/?utm_source=rss&utm_medium=rss&utm_campaign=error-handling-in-r"rel =" noreferrer>此博客文章:
Widely based on r2evans answer, here's how to do the same kind of things with withRestarts, with some helps from This blog post:
set.seed(2)
foo <- NULL
operation <- function(x,tries) {
message(paste("x is",x,"remaining tries",tries))
withRestarts(
tryCatch({
if (runif(1) < x) stop("fail!") else 1
},
error=function(e) { invokeRestart("retry")}),
retry = function() {
message("Retrying")
stopifnot(tries > 0)
operation(x,tries-1)
}
)
}
> operation(0.9,5)
# x is 0.9 remaining tries 5
# Retrying
# x is 0.9 remaining tries 4
# Retrying
# x is 0.9 remaining tries 3
# Retrying
# x is 0.9 remaining tries 2
# Retrying
# x is 0.9 remaining tries 1
[1] 1
这是一种递归调用，因此您可以在再次调用该函数之前做任何想做的事情.
It's a kind of recursive call, so you can do whatever you want before calling the function again.
您可以以相同的方式在tryCatch错误处理程序中执行此操作，使用重新启动处理程序的兴趣在于调用特定函数，如果您有两个想要几乎相同的处理程序行为的tryCatch，则可以添加参数并使用每次尝试捕获都使用相同的处理程序，即:
You may do it in the tryCatch error handler the same way, the interest to use restarts handlers is to call a specific function, if you had two tryCatch for which you want nearly same handler behavior then you can add a parameter and use the same handler for each try catch, i.e.:
testfun <- function(x) {
withRestarts({
tryCatch(
{
ifelse(runif(1) < 0.5,stop("Error Message"),warning("Warning message"))
},
warning=function(e) { invokeRestart("logger", level="warning", message=e ) },
error=function(e) { invokeRestart("logger", level="error", message=e ) }
)
},
logger = function(level,message) {
message(date()," [",level,"]: ",message[['message']])
}
)
}
给予:
> set.seed(2)
> testfun()
Fri Jul 29 14:15:11 2016 [error]: Error Message
> testfun()
Fri Jul 29 14:15:12 2016 [warning]: Warning message
> testfun()
Fri Jul 29 14:15:13 2016 [warning]: Warning message
> testfun()
Fri Jul 29 14:15:13 2016 [error]: Error Message
这里的主要兴趣是记录器方法的分解和减少代码重复.
Main interest here is the factorizing of the logger method and to reduce code duplication.
这篇关于错误时再次循环的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！