Ch06 - Nhan Dang Anh

7/30/2019 Ch06 - Nhan Dang Anh

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Nhndngnh

11/01/2013Phm Vit Hng Nhp mn x l nh 1


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Nhndng Qu trnh phn loiitng

itngcbiudin theo mt m hnh no

V gn chng vo mtlp (tn gi) da theo nhng quy lutv cc muchun.

V d:

Nhndngging ni

Nhndng khun mt Nhndng vn tay

Nhndngcm xc...

11/01/2013 Phm Vit Hng Nhp mn x l nh 2


3/37

Qu trnh nhndng Lachn m hnh biudinitng

Lachnlut ra quytnh (phng php nhndng) v suydin qu trnh hc

Hcnhndng Khi m hnh biudinc xc nh

M hnh tham s

M hnh cu trc

n qu trnh hcnhmcithin, iuchnhvic phn lp Nhndng l tm ra quy lut v thut ton gn i

tng vo lpca n



4/37

Hc c gim st da vo kinthcbittrc.

Kthut ny da vo mtthvinmuchun.

Mucnnhndngsc so snh vimuchun xc nhthucloi no.

Vnchyu l thitkhthng c th so

snh itngvimu nn tngi r rng vktqu v dnh gi hiuqu.



5/37

Hc khng gim st phitnh ra cc lp khc

nhau v xc nhctrngcatnglp

Kh khn xc nh tnh chnh xc cakiuhc

ny v khng c thvinmu so snh

Kthutnhmhp cc nhm theo mt cch ti

unht.



6/37

Trong kthut ny th itngcbiudin

bngmt vectornhiuchiu.

Michiu l mt tham sthhinmtcim

caitng

Mts khi nim

Phn hoch khng gian Hm phn lphoc hm ra quytnh



7/37

Gis khng gian itng X

Th P l phn hoch khng gian X thnh cc lp

sao cho

Trong trnghp thng thng th khng gian ch

c thc phn tch tngphn


miXX i ,...,2,1,

XCC ii ,

XCjiCC i

m

iji

1,,


8/37

phn itng ra cc lp ta cn xc nhs

lp v ranh giigia cc lp

Hm phn lps gip phn bit cc lp

Nu c k lp th phi c k-1 hm phn lp



9/37

Hm phn lpthng l hm tuyn tnh

Khi hm tuyn tnh ny sgi l mtphng phn

lp (Hyperplane)

Hm thngcdngda trn khong cch

hocthng k


kkXWXWWXg ...)( 110


10/37

Mtsthut ton tiu biu

Thut ton da vo khong cch lnnht

Thut ton k trung bnh (K-mean)

Thut ton ISODATA

Thut ton k lng ging (K-nearest neighbor)



11/37

Vimttpgm m itng

Khong cch gia cc itng c thc xc

nhnh l ilng phn lp

Khong cch lnnhtngviphnt xa nht

to nn lpmi

S phn lps hnh thnh dndnda vo victnh khong cch gia cc itng v cc lp



12/37

Bc 1:

Chnht nhn ban u: Xi C1 l lp g1vi Z1 l phn

t trung tm (phnt c khong cch trung bnh ti cc

phnt khc trong g1)

Tnh ttc cc khong cch Dj1 = D(Xj,Z1) vi j = 1..m

Tm Dk1lnnht. Xk l phnt xa nhtca nhm g1

Xktr thnh phnt trung tm Z2calpmi g2.

Tnh d1=D12=D(Z1,Z2)



13/37

Bc 2:

Tnh cc khong cch Dj1,Dj2vi j = 1..m

t Dk l khong cch lnnht

iukinkt thc

Nu Dk < d1kt thc thut ton (phn lp xong)

Nu khng sto nn lp g3 c Xk l phnt trung tm Z3

Tnh d3=(D12+D13+D23)/3

Thut ton lpilpli cho n khi kt thc



14/37

y l thut ton da vo K phntu tin

trong khng gian (xc nh K lpvi K cho

trc)

tng l tm K lp sao cho khong trung bnh

gia cc phnt v tm calp cc phnt ny

thuc l nhnht

Da vo cng thc:


kj

N

j

jk CXXN

Z

,1

1


15/37

Chn K phntu tin

Chnbtkhocda vo quy lut cho trc

VD: Hai phnt xa nht

L K phnt trung tm ca K lp



16/37

Thchin phn lp Xt lnltvimi X, X Gknu D(X,Zk) l nhnht

vimi k = 1..K

Tnh li Zk sau milncpnht thnh vin theo cngthc

Tip tcvitng X cho nht

Lpli qu trnh phnlp cho n khi khng cn s thay

iphnt trung tm


kj

N

j

jk CXXN

Z

,1

1


17/37

ISODATA l Iterative SelfOrganizing Data

Analysis

Thut ton ny tngimmdo v khng c

nh cc lp



18/37

Cc bc: Lachn phn hochda vo cc tm btk (ktqu khng

phthuc vo tm ban u ny)

Phn vng bng cch t cc im vo lp c tm gnnht

da vo khong cch Tch ilp ban unukhong cch lnhnngng t1 Xc nh phn hochmida vo cc tm va xc nh cho

n khi khng c tm mi

Nhm cc vng theo ngng t2 Lp cc bc trn cho n khi tha mn tiu chun

phn hoch



19/37

Thut ton ny da vo v tr caitngcn

xt xc nhlpitngthucv l lp

no

Cc muscbiudin trn khng gian itng

Miitngcn xc nhlps tm k mugnnht

xung quanh

itngu vo ny sthuclp c slngln

nht trong s k lng ging



20/37

V thut ton chnsngquytnhvic

phn lp nn thng thnglplnnht trong tp

muthng c xu hngthngtr

lm gimvic ny th trngs lin quan n

khong cch c thc thm vao, v mu cng

xa s c nhhng t hn so vimu gn



21/37

Ngoi cch biudinnhlng th cn tntikiuitngnh tnh

V dmi quan hgia cc itnghocdng

caitng Gisitng c thcbiudinbimt

chui k t v mi k tsthhinmtc tnh

Hm phn bits l hm logic nhndin cc tc cng di



22/37

C hai giai on trong quy trnh nhndin:

Xc nh quy tc xy dng

Xc nh cc dngda vo cc quy tc

Trong hai giai on th xc nh quy tc xy dng

l rt kh khn v l vn chnh cngiiquyt

trong quy trnh nhndindng ny



23/37

Mngnron bao gmnhiuphntx l n

ginhotng song song.

Tnh nngcahthngphthuc vo cu trc

lin ktgia cc nron v trngsca cc lin

kt ny

Trong mngnron c cc nronu vo v cc

nronu ra



24/37

Mng Hopfield l mngn ron

1 lp NN

nh xdliu tnh hiu vo sang t hiu ra theo kiu

tkthp Nu tn hiu vo l X thucmin D th tn hiu ra Y cngthuc

min D

Mng Hopfield m phngkhnnghitngca no

ngi (nhn ra ngi quen khi nhn ra cc nt quen

trn khun mt)



25/37

Mng Hopfield c mtlp ra c kch thcbng

kch thc tn hiu vo, lin ktn ron l y.

Mng Hopfield yu cu tn hiu vo c gi trlngcc -1 v 1



26/37

Hm kch hotti cc n ron l:

Wij l trngsca lin ktgian ron th i vi

n ron th j


j ijij

j ijij

isw

swa

,1

,1


27/37


28/37

Gisa vo mng vector tn hiu X

Vic tnh ton u ra Y cho tn hiu X l qu trnh

lpli:

t X0=X

Tnh Yt l tn hiuu ra tngngvi Xt lan truyn

trong mngmtln

Nu Yt khc Xt th tiptcvi t=t+1 v Xt+1 = Yt Nu Yt=Xt th dngli v ktqucamng l Yt

W khng thay i trong qu trnh tnh Y



29/37

Mt vi tnh hung c thny sinh

Mng khng dng

Mng c tha ra lun phin mt vi muhchocnh

ngcca chng

Mngdng v Xt=X

X conngda trn muhc, X c th l mt

trong cc muhc



30/37

Mt vi tnh hung c thny sinh (tt)

Mngdngvi Xt l Xs no trong muhc

Mngphchi nguyn dngca X chnh l Xs

Mngdngvi Xt khng thucmuhc

Chra mt vectormi c th dng cpnhttrngs

Mngdngvi Xt l nhngcca cc trnghp

2,3,4



31/37

Mng Kohonen tp trung vo mi lin h c tnh

cu trc trong cc vng ln cnhoc trong ton

th khng gian mu

Trong mng Kohonen cc vector tn hiu vo gn

nhau sc nh x sang cc n ron trong mng

ln cn nhau



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Mng Kohonen rtgnvimng sinh hcvcutolncchhc

Mng Kohonen c mtlp kch hot l cc n ronc phn b trong mtphng hai nhiukiulivung hoclc gic

Phn b ny lm cho min ron c cng sn rontrong tnglp lng ging v cc u vo tngt

nhau s kch hot cc n ron gn nhau (khng gian 2chiusphiccun thnh mt khng gian lintip)



33/37

Ttc cc n ron lp kch hotcniy

vilp vo miktni ny s c mttrngs

Cc n ron trn lp kch hotchnivi cc lp

ln cn nn khi c tin hiuu vo schto ra

kch hotaphng

Vng c kch hotschra v tr ca tn hiu

u vo trong khng gian itng



34/37

Vichcca mang kohonen da trn kthutcnhtranh khng cnmuhc.

Trngsca cc n ron ckhitobngmts

btknh Mngchc qua mtlnglnmugn nhau v

thngnhiuln theo cc vng lp

Timtthiimchc mtn ron duy nht C tronglp kch hotclachnvi nguyn tc l n ron

C c vectortrngsgnvi tn hiu vo nht



35/37

Sau khi c n ron C, cc trngs wcichiu

chnhnhm cho gnvitrngs mong mun (u

vo)

Nu tn hiu vo xsi v trngs wcitoktqu ra

qu ln th phigimtrngs v ngcli



36/37

Tlgimhoctngtrngssnhdn theo thigian v khong cch sai sgia vectoru vo vvectortrngsvi cng thc

Vi

s l thtbc

D(t) l vectoru vo t

u l sthtcan ron C cchn (u,v,s) l hm tlkhong cch gian ron v v u (c th l

hm ngnghoc hm Gaussian)


))()()((),,()()1( swtDssvuswsw vvv


37/37

V mng Kohonen chunluynda vo s

kch hotaphng v cc n ron ln cn nn

cc itnggn nhau s kch hot cc n ron

gn nhau

Khi chuynmt tn hiuu vo vo mng th mt

vng n ron sc kch hot cho chng ta thy

tn hiuu vo ny thuc vng dliu no

Ch06 - Nhan Dang Anh

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