pd-merge outer on empty-dataset

[harold]

I'm doing a reduce to align a bunch of datasets on a shared column.

I used (ds/empty-dataset) as my initial value for the reduce, and the reducer boiled down to something like this:

analysis.core> (join/pd-merge (ds/empty-dataset)
                              (ds/->dataset {:t [0 1] :x [:a :b]})
                              {:on :t :how :outer})
Execution error at tech.v3.dataset.impl.dataset.Dataset/column (dataset.clj:306).
Column not found: :t

I think I get why that happened, and I'm not sure if that should even really work, but it was unexpected, to me.

This is how I'm working around it for now:

analysis.core> (join/pd-merge (ds/->dataset {:t []})
                              (ds/->dataset {:t [0 1] :x [:a :b]})
                              {:on :t :how :outer})
outer-join [2 2]:

| :t | :x |
|---:|----|
|  0 | :a |
|  1 | :b |