18 Adding rows from another table

add_rows stacks another table underneath this one. Nothing is matched and no column is added; the rows just carry on where the first table stopped.

more <- data.frame(
  region = "North", product = "Sprocket", revenue = 400, cost = 120,
  stringsAsFactors = FALSE
)

sales |> add_rows(more) |> take(6)

region	product	revenue	cost
West	Widget	100	40
West	Widget	200	50
West	Gadget	300	100
West	Gadget	150	50
East	Widget	500	100
North	Sprocket	400	120

more = pd.DataFrame({
    "region": ["North"], "product": ["Sprocket"],
    "revenue": [400], "cost": [120],
})

sales >> add_rows(more) >> take(6)

region	product	revenue	cost
West	Widget	100	40
West	Widget	200	50
West	Gadget	300	100
West	Gadget	150	50
East	Widget	500	100
North	Sprocket	400	120

Both tables need the same columns. A column on one side only is refused rather than filled in with missing values, because a half-empty column that says nothing is how a mistake survives to the end of a pipeline.

collect(sales |> add_rows(data.frame(region = "North")))

Error:
! `add_rows` needs the other table by name: add_rows(more_sales)

try:
    collect(sales >> add_rows(pd.DataFrame({"region": ["North"]})))
except GodError as refusal:
    print(refusal)


illegal: `add_rows` needs both tables to have the same columns: this table has product, revenue, cost and `table` does not. Add what is missing, or drop it with `pick`
  |
2 |   then add_rows table
  |        ^^^^^^^^^^^^^^