Big Data and a fwf files reading with filters
Try the LaF package. See this:
https://stackoverflow.com/a/24716798/1427069

Once you create a laf object, you can create a data frame or data table using your row filter condition.

library(LaF)
laf &lt;- laf_open_fwf("foo.dat",
                    column_widths = colWidths, 
                    column_types=rep("character", length(colWidths)),
                    column_names = colNames)
castData &lt;- laf[RecordID == "Cast", ]