Debugging lapply/sapply calls

Question

Code written using lapply and friends is usually easier on the eyes and more Rish than loops. I love lapply just as much as the next guy, but how do I debug it when things

Answer 1

If you wrap your inner function with a try() statement, you get more information:

> sapply(x, function(x) try(1/x))
Error in 1/x : non-numeric argument to binary operator
[1] "-0.5"                                                    
[2] "Error in 1/x : non-numeric argument to binary operator\n"
[3] "Inf"                                                     
[4] "1"                                                       
[5] "0.5"

In this case, you can see which index fails.