[{hasCar:true,travels:[{_id:1,distance:50},{_id:2,distance:150},{_id:3,distance:70},{_id:4,distance:200},{_id:5,distance:150},{_id:6,distance:50},]},{hasCar:false,walks:[{_id:1,steps:847},{_id:2,steps:82},{_id:3,steps:200},{_id:4,steps:1812},{_id:5,steps:350},{_id:6,steps:825},{_id:7,steps:210}]},{hasCar:true,travels:[{_id:1,distance:50},{_id:2,distance:954},{_id:3,distance:70},{_id:4,distance:85},{_id:5,distance:150},{_id:6,distance:50},]},{hasCar:false,walks:[{_id:1,steps:847},{_id:2,steps:1025},{_id:3,steps:200},{_id:4,steps:754},{_id:5,steps:350},{_id:6,steps:1520},{_id:7,steps:210}]},{hasCar:true,travels:[{_id:1,distance:50},{_id:2,distance:150},{_id:3,distance:48},{_id:4,distance:185},{_id:5,distance:150},{_id:6,distance:10},]},{hasCar:false,walks:[{_id:1,steps:847},{_id:2,steps:1125},{_id:3,steps:200},{_id:4,steps:965},{_id:5,steps:350},{_id:6,steps:152},{_id:7,steps:3250}]},{hasCar:true,travels:[{_id:1,distance:850},{_id:2,distance:32},{_id:3,distance:75},{_id:4,distance:85},{_id:5,distance:384},{_id:6,distance:750},]},{hasCar:false,walks:[{_id:1,steps:95},{_id:2,steps:268},{_id:3,steps:723},{_id:4,steps:235},{_id:5,steps:1025},{_id:6,steps:854},{_id:7,steps:785}]}]

db.collection.aggregate([{"$facet":{"avgSteps":[{"$match":{hasCar:false}},{$project:{steps:{$avg:"$walks.steps"}}}],"sumDistance":[{"$match":{hasCar:true}},{$project:{sumKm:{$sum:"$travels.distance"}}}],}}])