Disregarding simple warnings/errors in tryCatch()
r, try-catch, warnings
Solution
I think you're looking for the difference between `tryCatch`, which catches a condition and continues evaluation from the environment where the tryCatch was defined, versus `withCallingHandlers`, which allows you to 'handle' a condition and then continue on from the location where the condition occurred. Take a look at `warning` (or the help page for warning, but that's less fun), especially the lines
withRestarts({
.Internal(.signalCondition(cond, message, call))
.Internal(.dfltWarn(message, call))
}, muffleWarning = function() NULL)
This says -- signal a condtion, but insert a 'restart' where the condition was signaled from. Then you'd
withCallingHandlers({
warning("curves ahead")
2
}, warning = function(w) {
## what are you going to do with the warning?
message("warning occurred: ", conditionMessage(w))
invokeRestart("muffleWarning")
})
Although `withCallingHandlers` is often used with warnings and `tryCatch` with errors, there is nothing to stop one from 'handling' an error or catching a warning if that is the appropriate action.
Problem
I'm a huge fan of `tryCatch()`. However, until today I never really paid attention to the distinction between simple and regular warnings/errors and thus I don't really know how to handle them. Actual question What I'd like to know is how to tell `tryCatch` (see help file) that simple warnings are OK and that it should return the result of `expr` instead of jumping to the `warning` section. Below you'll find a reproducible example No `tryCatch` >> no warning ``` require("forecast") y <- ts(c(6178, 7084, 8162, 8462, 9644, 10466, 10748, 9963, 8194, 6848, 7027, 7269, 6775, 7819, 8371, 9069, 10248, 11030, 10882, 10333, 9109, 7685, 7602, 8350, 7829, 8829, 9948, 10638, 11253, 11424, 11391, 10665, 9396, 7775, 7933, 8186, 7444, 8484, 9864, 10252, 12282, 11637, 11577, 12417, 9637, 8094, 9280, 8334, 7899, 9994, 10078, 10801, 12950, 12222, 12246, 13281, 10366, 8730, 9614, 8639, 8772, 10894, 10455, 11179, 10588, 10794, 12770, 13812, 10857, 9290, 10925, 9491, 8919, 11607, 8852, 12537, 14759, 13667, 13731, 15110, 12185, 10645, 12161, 10840, 10436, 13589, 13402, 13103, 14933, 14147, 14057, 16234, 12389, 11595, 12772)) out <- forecast::auto.arima(x=y) > out Series: y ARIMA(4,1,1) Coefficients: ar1 ar2 ar3 ar4 ma1 0.6768 -0.2142 0.5025 -0.7125 -0.8277 s.e. 0.0749 0.0889 0.0874 0.0735 0.0485 sigma^2 estimated as 915556: log likelihood=-780.33 AIC=1572.65 AICc=1573.62 BIC=1587.91 ``` `tryCatch` >> simple warning When I wrap it with `tryCatch`, it detects a simple warning that will cause my `expr` block to be "skipped" in favor of the `warning` section. Thus the function does not return the estimation result, but the simple warning. ``` mod <- tryCatch( out <- forecast::auto.arima(x=y), error=function(e) { print(e) }, warning=function(w) { print(w) } ) > mod <simpleWarning in kpss.test(x): p-value smaller than printed p-value> ``` Current workaround ``` if (any(class(mod) == "simpleWarning")) { mod <- forecast::auto.arima(x=y) } > mod Series: y ARIMA(4,1,1) Coefficients: ar1 ar2 ar3 ar4 ma1 0.6768 -0.2142 0.5025 -0.7125 -0.8277 s.e. 0.0749 0.0889 0.0874 0.0735 0.0485 sigma^2 estimated as 915556: log likelihood=-780.33 AIC=1572.65 AICc=1573.62 BIC=1587.91 ```