How to run a model stored as a .Rda file?

Question

I am using an already written R code which has a line of code as shown below

model_predictors <- buildModel(flag, data, outcomeName, folder)
model<-model_predictors$model
predictorsNames<-model_predictors$predictorsNames
auc <- model_predictors$auc
save(model, file=paste(folder,studyName,'_model_', flag$model[1], '_', outcomeName,".Rda",sep=''))

As you can see in the last line of code, the (training) model is saved in folder in a .Rda file format with a naming convention _model_. Now, I have to use this model to test/evaluate on unseen dataset.

So now my question, I see a .Rda file in my folder path and I can load the .Rda file in Rstudio but how do I make inference from this model? I am new to R and can anyone help me with this please?

Can someone help me understand how to run this model please?

Answer 1

I suppose you come from Python. R is quite different as it does not require to save to external files your model, you just need to have it in your workspace. Once you have a model object, you just have to use the predict function and specify the unseen dataset. Here's an example of a tree model:

model<-tree(Y~X1+X2, data=dataset) #estimate of the tree model
predictions<-predict(model, newdata=unseen_dataset) #prediction on new data

Be sure variable names between datasets correspond.