Why does load(...) return character name of object instead of the object itself?

Question

The svm model is created with the package e1071 in R. To use the model, I need to save it and read as needed. The package has write.svm, but does not have read.svm. If I use

model <- svm(x, y)

save(model, 'modelfile.rdata')
M <- load('modelfile.rdata')

object M contains just the word 'model'.

How to save the svm model and read back later, to apply to some new data?

Answer 1

Look at the return value for the function load in the help file:

Value:

 A character vector of the names of objects created, invisibly.

So "model" is indeed the expected value of M. Your svm has been restored under its original name, which is model.

If you find it a bit confusing that load does not return the object loaded but instead restores it under the name used in saving it, consider using saveRDS and readRDS.

saveRDS(model, 'modelfile.rds')
M <- readRDS('modelfile.rds')

and M should contain your svm model.

I prefer saveRDS and readRDS because with them I know what objects I'm creating in my workspace - see the blog post of Gavin Simpson (linked in his answer) for a detailed discussion.