Fread autofill NA or NULL for empty columns

[markdanese]

I have a file with 10 columns. The first 4 are always filled with a person's basic information. The last 6 may, or may not, have data in them, and they are filled in order (e.g., column 1, column 2, . . . , column 6). When the first empty field occurs (for example, after column 4), the line ends. It would be great to autofill NA for the remaining columns. Read.delim handles it, albeit slowly. In this case, fread can't detect the number of columns properly, even with header = T, because almost no rows have data in all columns.

[mattdowle]

Agreed, would be great.
But closing since duplicate of #536.