Convert the frame into a dictionary of lists, by columns.
The order of records in the dictionary will be the same as the order of columns in the frame.
.ncols records. Each record
represents a single column: the key is the column’s name, and the
value is the list with the column’s data.
DT = dt.Frame(A=[1, 2, 3], B=["aye", "nay", "tain"]) DT.to_dict()