英文:
using try vs TryCatch in R
问题
我的R代码如下：
errors = 0
for(i in c(1:100)){
tryCatch(expr = {
API调用
}, error = {errors=errors+1}, finally = {})
后续代码
}
这段代码的目的是即使API调用失败，也要继续执行，并计算出错误发生的次数。
但是我发现，如果在某次迭代中API调用出现错误，那么后续的迭代代码将不会执行。
如果我使用try()，那么我将无法计算错误的次数。
英文:
My R code is as follows
errors = 0
for(i in c(1:100)){
tryCatch(expr = {
API Call
}, error = {errors=errors+1}, finally = {})
further code
}
The code is meant to continue execution even if the API call fails and count the number of times error occurred.
But I see that if for an iteration there is an error in API call, the code is not executed for further iterations.
If I use try(), then I wont be able to count the number of errors.
答案1
得分: 3
tryCatch函数的error=参数应该是一个函数。如果在for循环之前预先实例化errors <- 0，有几种选择：
我更喜欢的是捕获并检查是否继承了"error"：
errors <- 0L
for (...) {
res <- tryCatch({
...API调用...
},
error = function(e) e)
if (inherits(res, "error")) {
errors <- errors + 1L
} else {
这里是其他操作
}
}
等效的方式是使用try：
errors <- 0L
for (...) {
res <- try({
...API调用...
}, silent = TRUE)
if (inherits(res, "try-error")) {
errors <- errors + 1L
} else {
这里是其他操作
}
}
虽然我更喜欢这种方式可能主要是主观的原因。另一种方式是更内部的：
errors <- 0L
for (...) {
res <- tryCatch({
...API调用...
},
error = function(e) { errors <<- errors + 1L; })
这里是其他操作
}
英文:
The error= argument of tryCatch should be a function. If you pre-instantiate errors <- 0 before the for loop, there are a couple of options:
My preferred is to catch and check to see if it inherits "error":
errors <- 0L
for (...) {
res <- tryCatch({
...API call...
},
error = function(e) e)
if (inherits(res, "error")) {
errors <- errors + 1L
} else {
something else here
}
}
Equivalently with try:
errors <- 0L
for (...) {
res <- try({
...API call...
}, silent = TRUE)
if (inherits(res, "try-error")) {
errors <- errors + 1L
} else {
something else here
}
}
Though the reasons I prefer that may be mostly subjective. Another way would be more internal:
errors <- 0L
for (...) {
res <- tryCatch({
...API call...
},
error = function(e) { errors <<- errors + 1L; })
something else here
}
答案2
得分: 0
# 设置场景
api_call <- function(in_1){
if(in_1 %in% c(5,7)){
stop("bad num")
}
in_1 + 0.5
}
for(i in 1:10){
print(api_call(i))
}
# 封装函数
library(purrr)
safe_api_call <- safely(api_call)
for(i in 1:10){
print(safe_api_call(i)$result)
}
# 添加错误计数
error_count <- 0
for(i in 1:10){
r <- safe_api_call(i)
print(r$result)
error_count <- error_count + inherits(r$error, "error")
}
error_count
以上是要翻译的内容。
英文:
# set up scenario
api_call <- function(in_1){
if(in_1 %in% c(5,7)){
stop("bad num")
}
in_1+.5
}
for(i in 1:10){
print(api_call(i))
}
# wrap it up
library(purrr)
safe_api_call <- safely(api_call)
for(i in 1:10){
print(safe_api_call(i)$result)
}
# add counting of errors
error_count <- 0
for(i in 1:10){
r <- safe_api_call(i)
print(r$result)
error_count <- error_count + inherits(r$error,"error")
}
error_count
</details>
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