A logical, when set to TRUE the resulting data.frame contains all
possible pairs of origins and destination, even if the data in the
sp_network_pair-class() does not have them.
Value
A single data.frame, combining all available information on origins, destinations and OD pairs
# NOT RUN {# long form data for flows from Germany to Germanypair_merge(multi_net_usa_ge,"ge_ge")
# long form data for flows from Germany to USApair_merge(multi_net_usa_ge,"ge_usa")
# }