Question

I have a large dataset called “inputs”. One of the columns in the dataset is a flag called “constrained” with either “Y” or “N”. I want to create two datasets where one is the rows where the flag is “Y” and one is the rows where the flag is “N”.

I tried:

ifelse(inputs$constrained == "N",unconstrained <- inputs,constrained <- inputs)

but both datasets unconstrained and constrained are identical to inputs.

What am I doing wrong?

Answer 1

first <- split(inputs, inputs$constrained)[1]
second <- split(inputs, inputs$constrained)[2]

If you wanted to use “[” you could do this:

 unconstrd <- inputs[ inputs$constrained == "N" , ]
 constrd <-  inputs[ ! inputs$constrained == "N" , ]

Both of that second option might have entries where ‘constrained’ is NA, due the screwy way that R handles NA conditionals although it would not be a faithful reflection of those rows. (I admit I did not sure what the split method does with NA’s.) I just tested the split method and it might be superior, since (like subset) it does not return the is.na(input$constrained) rows.