R foreach stop iteration at i











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down vote

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I am using R package foreach.
When bug exists in foreach block, it's hard to re-occur it and hard to debug.



Take the following script as example.
I want to stop at i=4 to check what's wrong. However, it stops at i=10.



Any solution?



library(foreach)
foreach(i = icount(10)) %do% {
if (i == 4){
e <- simpleError("test error")
stop(e)
}
}









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  • 2




    Eventually you want use break ... (documentation of for (...))
    – jogo
    Nov 21 at 12:31












  • for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
    – Dongdong Kong
    Nov 21 at 13:02















up vote
0
down vote

favorite
1












I am using R package foreach.
When bug exists in foreach block, it's hard to re-occur it and hard to debug.



Take the following script as example.
I want to stop at i=4 to check what's wrong. However, it stops at i=10.



Any solution?



library(foreach)
foreach(i = icount(10)) %do% {
if (i == 4){
e <- simpleError("test error")
stop(e)
}
}









share|improve this question


















  • 2




    Eventually you want use break ... (documentation of for (...))
    – jogo
    Nov 21 at 12:31












  • for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
    – Dongdong Kong
    Nov 21 at 13:02













up vote
0
down vote

favorite
1









up vote
0
down vote

favorite
1






1





I am using R package foreach.
When bug exists in foreach block, it's hard to re-occur it and hard to debug.



Take the following script as example.
I want to stop at i=4 to check what's wrong. However, it stops at i=10.



Any solution?



library(foreach)
foreach(i = icount(10)) %do% {
if (i == 4){
e <- simpleError("test error")
stop(e)
}
}









share|improve this question













I am using R package foreach.
When bug exists in foreach block, it's hard to re-occur it and hard to debug.



Take the following script as example.
I want to stop at i=4 to check what's wrong. However, it stops at i=10.



Any solution?



library(foreach)
foreach(i = icount(10)) %do% {
if (i == 4){
e <- simpleError("test error")
stop(e)
}
}






r parallel-foreach






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share|improve this question











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share|improve this question










asked Nov 21 at 12:26









Dongdong Kong

197




197








  • 2




    Eventually you want use break ... (documentation of for (...))
    – jogo
    Nov 21 at 12:31












  • for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
    – Dongdong Kong
    Nov 21 at 13:02














  • 2




    Eventually you want use break ... (documentation of for (...))
    – jogo
    Nov 21 at 12:31












  • for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
    – Dongdong Kong
    Nov 21 at 13:02








2




2




Eventually you want use break ... (documentation of for (...))
– jogo
Nov 21 at 12:31






Eventually you want use break ... (documentation of for (...))
– jogo
Nov 21 at 12:31














for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
– Dongdong Kong
Nov 21 at 13:02




for (...) is not suit. Because foreach can be easily modified into parallel mode. modifying foreach into for every time when debugging, is a little tired.
– Dongdong Kong
Nov 21 at 13:02












1 Answer
1






active

oldest

votes

















up vote
1
down vote













One option to handle this is with a browser() inside a tryCatch as in:



foreach(i = icount(10)) %do% {
tryCatch(
if (i == 4){
e <- simpleError("test error")
stop(e)
},
error = function(e) browser()
)
}


This will produce a browser of the environment at the time of the error, which will allow you to inspect any objects and/or debug your code.



Your console will then look like the following and you can ask what the value of i is. Like this:



Browse[1]> i



[1] 4






share|improve this answer























  • It works. Thank you!
    – Dongdong Kong
    Nov 22 at 1:26











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
1
down vote













One option to handle this is with a browser() inside a tryCatch as in:



foreach(i = icount(10)) %do% {
tryCatch(
if (i == 4){
e <- simpleError("test error")
stop(e)
},
error = function(e) browser()
)
}


This will produce a browser of the environment at the time of the error, which will allow you to inspect any objects and/or debug your code.



Your console will then look like the following and you can ask what the value of i is. Like this:



Browse[1]> i



[1] 4






share|improve this answer























  • It works. Thank you!
    – Dongdong Kong
    Nov 22 at 1:26















up vote
1
down vote













One option to handle this is with a browser() inside a tryCatch as in:



foreach(i = icount(10)) %do% {
tryCatch(
if (i == 4){
e <- simpleError("test error")
stop(e)
},
error = function(e) browser()
)
}


This will produce a browser of the environment at the time of the error, which will allow you to inspect any objects and/or debug your code.



Your console will then look like the following and you can ask what the value of i is. Like this:



Browse[1]> i



[1] 4






share|improve this answer























  • It works. Thank you!
    – Dongdong Kong
    Nov 22 at 1:26













up vote
1
down vote










up vote
1
down vote









One option to handle this is with a browser() inside a tryCatch as in:



foreach(i = icount(10)) %do% {
tryCatch(
if (i == 4){
e <- simpleError("test error")
stop(e)
},
error = function(e) browser()
)
}


This will produce a browser of the environment at the time of the error, which will allow you to inspect any objects and/or debug your code.



Your console will then look like the following and you can ask what the value of i is. Like this:



Browse[1]> i



[1] 4






share|improve this answer














One option to handle this is with a browser() inside a tryCatch as in:



foreach(i = icount(10)) %do% {
tryCatch(
if (i == 4){
e <- simpleError("test error")
stop(e)
},
error = function(e) browser()
)
}


This will produce a browser of the environment at the time of the error, which will allow you to inspect any objects and/or debug your code.



Your console will then look like the following and you can ask what the value of i is. Like this:



Browse[1]> i



[1] 4







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 21 at 17:31

























answered Nov 21 at 17:25









Ian Wesley

2,543526




2,543526












  • It works. Thank you!
    – Dongdong Kong
    Nov 22 at 1:26


















  • It works. Thank you!
    – Dongdong Kong
    Nov 22 at 1:26
















It works. Thank you!
– Dongdong Kong
Nov 22 at 1:26




It works. Thank you!
– Dongdong Kong
Nov 22 at 1:26


















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