# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^([^,]*),([^,]*),([^,]*),(.*)/$2 - $3=[[$1,[\4]]]/gm;t' <<< "StreetA @ StreetB,1 NameA,DirectionA,Lat,Long
StreetC @ StreetD,1 NameA,DirectionA,Lat,Long
StreetE @ StreetF,1 NameA,DirectionB,Lat,Long
StreetG @ StreetH,1 NameA,DirectionB,Lat,Long
StreetI @ StreetJ,2 NameB,DirectionC,Lat,Long
StreetK @ StreetL,2 NameB,DirectionC,Lat,Long
StreetM @ StreetN,2 NameB,DirectionD,Lat,Long
StreetO @ StreetP,2 NameB,DirectionD,Lat,Long"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html