5.3.1 Netflix Prize

The Netflix Prize amagwiritsa kuitana lotseguka kulosera mafilimu anthu mukufuna.

Pulojekiti yotchuka kwambiri yotsegula ndi mphoto ya Netflix. Netflix ndi kampani yopanga mafilimu pa intaneti, ndipo mu 2000 iyo inayambitsa Cinematch, ntchito yotsimikizira mafilimu kwa makasitomala. Mwachitsanzo, Cinematch ikhoza kuona kuti mumakonda Star Wars ndi Empire Strikes Back ndikupemphani kuti muwonenso Kubwerera kwa Jedi . Poyamba, Cinematch inkagwira ntchito bwino. Koma, kwa zaka zambiri, adapitirizabe kukwanitsa kulongosola zomwe ma kasitomala angasangalale nawo. Koma pofika chaka cha 2006, cinematch idapita patsogolo. Ofufuza pa Netflix ayesa zonse zomwe angaganize, koma panthawi yomweyi, akuganiza kuti pali mfundo zina zomwe zingawathandize kusintha kayendedwe kawo. Kotero, iwo anabwera ndi zomwe zinali, panthawiyo, yankho lalikulu: kutsegula koyera.

Chofunika kwambiri kuti mphoto ya Netflix ikwaniritsidwe ndi momwe maitanidwe apangidwira, ndipo mapangidwewa ali ndi maphunziro ofunikira momwe maitanidwe otseguka angagwiritsidwe ntchito pofufuza kafukufuku. Netflix sanangotchulapo pempho losavomerezeka, zomwe anthu ambiri amaganiza atangoyamba kufufuza. M'malo mwake, Netflix anali ndi vuto lomveka bwino ndi njira yosavuta yowonetsera: iwo adatsutsa anthu kuti agwiritse ntchito mafilimu 100 miliyoni kuti awonetsere ziwerengero zitatu za mafilimu omwe adawagwiritsa ntchito koma Netflix sanamasulire. Munthu woyamba kukhazikitsa ndondomeko yolondola yomwe inaneneratu kuti miyezi itatu yokwana 10% imakhala yabwino kusiyana ndi Cinematch idzapambana madola milioni. Izi zowoneka ndi zosavuta kugwiritsa ntchito ndondomeko yoyezetsa-kufanizitsa ziŵerengero zomwe zinanenedwa ndi ziwerengero zomwe zinatchulidwa-zikutanthauza kuti mphoto ya Netflix inakhazikitsidwa kotero kuti njira zowonjezera zowunika kusiyana ndi zopanga; izo zinasintha vuto la kukonza Cinematch kukhala vuto loyitanidwa.

Mu October 2006, Netflix adamasula deta yomwe imakhala ndi mafilimu okwana 100 miliyoni kuchokera kwa makasitomala pafupifupi 500,000 (tidzakambirana zachinsinsi za kumasulidwa kwa deta mu chaputala 6). Deta ya Netflix ikhoza kulingalira ngati makina aakulu omwe ali makasitomala pafupifupi 500,000 ndi mafilimu 20,000. M'mbuyomuyi, panali zowerengera pafupifupi 100 miliyoni pa mlingo wa nyenyezi imodzi kapena zisanu (tebulo 5.2). Vuto linali kugwiritsa ntchito deta yomwe anaiwona mu chikwati kuti ziwonetsere ziwerengero zitatu zomwe zinayikidwa.

Ofufuza ndi osokoneza padziko lonse lapansi anakumana ndi vutoli, ndipo pofika chaka cha 2008 anthu opitirira 30,000 anali kugwira ntchito (Thompson 2008) . Pakati pa mpikisanowo, Netflix adalandira zoposa 40,000 njira zothetsera mavuto ochokera ku magulu oposa 5,000 (Netflix 2009) . Mwachiwonekere, Netflix sakanatha kuwerenga ndi kumvetsetsa njira zonsezi. Chinthu chonsecho chinathamanga bwino, komabe, chifukwa njirazo zinali zophweka kufufuza. Netflix angangokhala ndi makompyuta akuyerekezera ziwerengero zomwe zinanenedweratu ndi ziwerengero zomwe zimagwiritsidwa ntchito pogwiritsa ntchito metric (yomwe imagwiritsidwa ntchito ndi mizere yambiri ya zolakwika za squared). Zinali zokhoza kupenda mwamsanga njira zomwe zinathandiza Netflix kulandira njira kuchokera kwa aliyense, zomwe zinakhala zofunikira chifukwa malingaliro abwino amachokera m'malo ena odabwitsa. Ndipotu, yankho lopambana linaperekedwa ndi gulu lomwe linayambidwa ndi ofufuza atatu omwe analibe chidziwitso choyambitsa machitidwe oyamikira mafilimu (Bell, Koren, and Volinsky 2010) .

Mbali imodzi yokongola ya mphoto ya Netflix ndiyi yomwe inathandiza kuti njira zonse zomwe zatchulidwazi ziwonekere mwachilungamo. Izi zikutanthauza kuti, pamene anthu adasankha ziwerengero zawo zodziwika, sanafunike kuika zidziwitso zawo, zaka zawo, mtundu wawo, amuna awo, chiwerewere chawo, kapena chirichonse chokhudza iwo okha. Zomwe analosera za pulofesa wotchuka wa Stanford anachitidwa chimodzimodzi ndi zomwe zimachokera kwa mwana wachinyamata m'chipinda chake. Mwamwayi, izi sizowona mufukufuku wambiri. Izi zikutanthauza kuti kafukufuku wamakhalidwe ambiri, nthawi yowunika ndi yochepa kwambiri. Choncho, malingaliro ambiri a kafukufuku saganiziridwa mozama, ndipo ngati malingaliro akuyesedwa, n'zovuta kufotokozera zomwezo kuchokera kwa wolenga malingaliro. Tsegulani mapulojekiti oyendetsa, komano, akhale ndi kafukufuku wosavuta ndi wowona kuti athe kupeza malingaliro omwe angawonongekenso.

Mwachitsanzo, nthawi ina pa mphoto ya Netflix, munthu wina yemwe ali ndi chithunzi chotchedwa Simoni Funk anaika pamutu pake njira yothetsera vutoli chifukwa cha kuwonongeka kwapadera, njira yochokera ku algebra yomwe siinagwiritsidwe ntchito kale ndi ena. Thumba la blog la Funk linali lofanana ndi luso komanso losavomerezeka. Kodi positiyi ya blogyi ikufotokoza njira yabwino yothetsera kapena inali kutaya nthawi? Kunja kwa polojekiti yotseguka, yankho likhoza kuti silinaphunzirepo mozama. Pambuyo pake, Simon Funk sanali pulofesa ku MIT; iye anali wopanga mapulogalamu a pulogalamu omwe, panthawiyo, anali kubwereranso ku New Zealand (Piatetsky 2007) . Ngati atumizira malingaliro awa kwa injini pa Netflix, ndithudi sizingatheke kuwerengedwa.

Mwamwayi, chifukwa ndondomekoyi yowoneka bwino ndi yosavuta kuigwiritsa ntchito, ziwerengero zake zomwe zinanenedwa zinayesedwa, ndipo zinawonekeratu kuti njira yakeyi inali yamphamvu kwambiri: iye anagwedezeka kufika pachinayi mu mpikisano, zotsatira zambiri zomwe magulu ena anali atakhala kale kugwira ntchito kwa miyezi pavuto. Pomalizira pake, mbali zake zogwiritsa ntchito zinagwiritsidwa ntchito ndi makampani onse ovuta (Bell, Koren, and Volinsky 2010) .

Mfundo yakuti Simoni Funk anasankha kulemba positi ya blog akufotokozera njira yake, m'malo moyesera kusunga chinsinsi, akuwonetsanso kuti ambiri omwe ali nawo mu Netflix Mphoto sadangotengeka ndi mphoto ya madola milioni. M'malo mwake, anthu ambiri omwe adawatsatila amawoneka kuti amasangalala ndi zovuta za nzeru ndi anthu omwe adayambitsa vutoli (Thompson 2008) , malingaliro omwe ndikuyembekeza kuti ochita kafukufuku ambiri amvetse.

Mphoto ya Netflix ndi chitsanzo chachiyero cha kuyitanidwa. Netflix adafunsa funso liri ndi cholinga chenichenicho (kuneneratu mafilimu) ndikupempha njira kuchokera kwa anthu ambiri. Netflix adatha kufufuza njira zonsezi chifukwa zinali zosavuta kufufuza kusiyana ndi kulenga, ndipo potsiriza Netflix anatenga njira yothetsera vutoli. Kenaka, ndikuwonetsani momwe njirayi ingagwiritsidwire ntchito mu biology ndi lamulo, ndipo popanda mphoto ya madola milioni.