scala - Reading and filtering a file into a string -

i new scala , need read contents of text file string while removing lines @ same time. lines removed can identified substring match. come following solution, works, problem newlines removed:

val fileasfilteredstring = io.source.fromfile("file.txt").getlines.filter(s => !(s contains "filter these")).mkstring; 

how can keep newlines?

add parameters mkstring:

val fileasfilteredstring = io.source.fromfile("file.txt").getlines     .filter(s => !(s contains "filter these")).mkstring("\n")