I understand ?
is used to access data, such as column
in Frame
, but the returned column
will be in float
.
How about assignment of new column in a Frame
?
let second = Series.ofValues(["d";"e";"f"])
let df?second = second
I tested this new column will stay as string
, actually, I just would like to know if there is a place that systematically explain the use of ?
operator.