Filtlong is a tool for filtering long reads by quality. It can take a set of long reads and produce a smaller, better subset. It uses both read length (longer is better) and read identity (higher is better) when choosing which reads pass the filter.
Filtlong builds into a stand-alone executable:
git clone https://github.com/rrwick/Filtlong.git
cd Filtlong
make -j
bin/filtlong -h