Read raw HEIMS file
fread_heims(filename)
A text-delimited file, passed to fread
from data.table
.
A data.table
with column names in ascending (lexicographical) order and
any columns starting with e
will be uppercase.
The strings "" "NA" "?" "." "*" "**"
are treated as missing, as well as ZZZZZZZZZZ
(so students without a CHESSN will be marked with the integer64
missing value).