cbinding data with different row number or row ids

[mb706]

Is there a way to make $cbind() behave like an outer join, so data with different rows can be added and the missing fields filled with NAs? See mlr-org/mlr3pipelines#216

[mllg]

Not very well tested yet, but should work.

[mb706]

I guess I would have to construct the cbind backend explicitly instead of using Task$cbind for this?

[mllg]

Is there an assertion in task$cbind() or why do you want to do this explicitly?

[mb706]

task$cbind() doesn't work:

> it = mlr_tasks$get("iris")
> it$cbind(data.table(x = 1:200))
Error in `[[<-.data.frame`(`*tmp*`, pk, value = 1:150) : 
  replacement has 150 rows, data has 200
> it$cbind(data.table(x = 1:100))
Error in `[[<-.data.frame`(`*tmp*`, pk, value = 1:150) : 
  replacement has 150 rows, data has 100

and even if it did work, there would probably need to be a mechanic to indicate which row of the new data belongs to which row of the task.

What does work is something like

> it$row_roles$use = (1:10) * 10  # say we want to put the new data on every 10th row
> it$cbind(data.table(z = 1:10))
> it$row_roles$use = 1:150

is this the intended way of doing this?

[mllg]

We should do a call to figure this out.

[mllg]

I guess it should be fine to manually fill with NAs in mlr3pipelines.