Azure, R: showing the Standard Error

Question

When I develop an experiment on Azure ML I have the chance to insert the "Execute R Script" module. When I have runned it, I can explore the outputs produced by the module itself.

My problem is that I have two modules: I do a filtering on a dataset in the first and use the resulting dataset in the second. Then I create a web service with it. Problem: when the filtering gives a null dataset this possibly create problems in the functions on the second module.

I want to find a way to "write" in the "Standard Error" space. I have tried to use:

if (length(dataset$column1)==0) {warning("Empty filtering!!!!")}

but it does not work.

Answer 1

According to the R manual for the NULL object, please try to use the function is.null(x) as the if condition.

Meanwhile, as notice, there are two similar concepts NA & NULL in R, please refer to the blog http://www.r-bloggers.com/r-na-vs-null/ to know the difference, and use the function is.na(x) instead of is.null(x) for a NA object.