Inserting rows into a dataframe based on a vector that contains dates

[Gabor Grothendieck]

There is an interesting problem on stackoverflow here:

http://stackoverflow.com/questions/35614766/inserting-rows-into-a-dataframe-based-on-a-vector-that-contains-dates/35614930#35614930

where a number of approaches failed due to memory size limitations but an sqldf solution worked because the computation is effectively done outside of R so R's memory limitations do not apply.