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TRNG I HC LC HNG
D ON KT QU HC TP
CA SINH VIN TRNG NGH
S DNG PHNG PHP HI QUY BAYES
GIO VIN HNG DN:
TS. HONG TH LAN GIAO
HC VIN THC HIN:
V TH NGC LIN
ng Nai, thng 09/2013 1
NI DUNG TRNH BY
I. Tng quan khai ph d liu v pht hin tri thc
II. H h tr ra quyt nh v m hnh h tr quyt nh
III. Phn tch hi quy
IV. D on kt qu hc tp da vo l thuyt phn lp
Naive Bayes
2
3
TNG QUAN KHAI PH D LIU V
PHT HIN TRI THC
Gii thiu v khai ph d liu (KPDL)
Khai ph tri thc t mt lng ln d liu
S dng d liu lch s khm ph nhng qui tc v ci
thin nhng quyt nh trong tng lai
4
Quy trnh pht hin tri thc
Hnh 1: Quy trnh pht hin tri thc
Bc 1: Hnh thnh, xc nh,
nh ngha bi ton
Bc 2: Thu thp, tin x l
d liu
Bc 3: Khai ph d liu rt ra
tri thc
Bc 4: Phn tch v kim nh
kt qu
Bc 5: S dng tri thc pht hin
c
5
H H TR RA QUYT NH
V M HNH H TR QUYT NH
6
H h tr ra quyt nh
HHTQ l nhng h thng my tnh tng tc nhm gip
nhng ngi ra quyt nh s dng d liu v m hnh gii
quyt cc vn khng c cu trc.
Cc thnh phn ca h h tr ra quyt nh
Phn h Qun l d liu
Phn h Qun l m hnh
Phn h Qun l da vo kin thc
Phn h Qun l giao din ngi dng
7
Vn dng phng php ton hc phn lp d liu
Khi nim v phn lp
Tin trnh x l nhm xp cc mu d liu hay cc i
tng vo mt trong cc lp c nh ngha trc.
K thut ph bin nht ca hc my v khai ph d liu.
8
Cc bc chnh gii quyt bi ton phn lp
Bc 1: Hc (Training): xy dng m hnh phn lp
Bc 2: Phn lp (classification): Bc ny s dng m hnh
phn lp c xy dng bc 1 kim tra,
nh gi v thc hin phn lp.
9
Cc k thut phn lp
Phng php da cy quyt nh
Phng php da trn lut
Phng php Naive Bayes
Mng Neuron
Phng php phn lp Naive Bayes
nh l Bayes
Tnh xc sut xy ra ca mt s kin ngu nhin A khi bit s
kin lin quan B xy ra.
Xc sut ny c k hiu l P(A|B)
c l "xc sut ca A nu c B".
10
Theo nh l Bayes, xc sut xy ra A khi bit B s ph thuc
vo 3 yu t:
P(A): Xc sut xy ra A ca ring n
P(B): Xc sut xy ra B ca ring n.
P(B|A): Xc sut xy ra B khi bit A xy ra
Khi bit ba i lng trn, xc sut ca A khi bit B cho bi
cng thc:
P A B =P B A P(A)
P(B)
11
M hnh phn lp Naive Bayes (NBC)
Mi mu c biu din bng X=(x1,x2,,xn) vi cc thuc
tnh a1, a2, , an.
Cc lp {C1, C2,,Cm} cho trc mu. NBC gn X vo Ci
nu P(X|Ci)>P(X|Cj) vi 1 j m, j # i (theo nh l Bayes).
phn lp mu cha bit X, ta tnh P(X|Ci)P(Ci) cho tng
Ci. NBC gn X vo lp Ci sao cho P(X|Ci)P(Ci) l ln nht.
12
Thut ton Naive Bayes
p dng trong bi ton phn loi, cc d kin gm c:
- D: tp d liu hun luyn c vector ha = (1, 2, , )
- Ci: phn lp i, vi i = {1,2,,m}.
- Cc thuc tnh c lp iu kin i mt vi nhau.
Theo nh l Bayes:
P Ci X =P(X|Ci)P(Ci)
P(X)
Theo tnh cht c lp iu kin:
P X Ci = P xk Ci
n
k=1
Trong :
- (|) xc sut thuc tnh th k mang gi tr xk khi bit X thuc phn lp i.
13
Cc bc thc hin thut ton phn lp Naive Bayes
Bc 1: Hun luyn Naive Bayes (da vo tp d liu), tnh
P(Ci)v P(Xk|Ci).
Bc 2: Phn lp Xnew=(x1,x2,xn). Xnew ta cn tnh xc
sut thuc tng phn lp khi bit trc Xnew. Xnew c
gn vo lp c xc sut ln nht theo cng thc:
14
max()
=1
V d: Tp d liu mu v kt qu hc tp ca sinh vin
TT Ni im vo Kinh t Gtinh Kt qu
1 Nng thn Trung bnh Thp N Rt
2 Thnh th Cao Trung bnh Nam u
3 Nng thn Thp Trung bnh Nam Rt
4 Thnh th Trung bnh Trung bnh N u
5 Thnh th Trungbnh Cao N u
6 Nng thn Cao Cao Nam u
7 Nng thn Trungbnh Cao N u
8 Thnh th Thp Thp Nam Rt
Yu cu: Phn lp cho mt th hin mi sau y
X= (kt qu l u () hay
Rt (R)). 15
Thc hin:
Bc 1: Ta c 2 lp =u, R= Rt, tng s mu =8
S mu c phn lp l 5 Xc sut u: P()=5/8
S mu c phn lp R l 3 Xc sut Rt: P(R) =3/8
t X1(lp ) = P P Xi i v X2 (lp R) = P R P Xi Ri
X1 = P().P(Noio = Nongthon|).P(Diemvao = thap|).
P(Kinhte = trungbinh|). P(Gioitinh = Nam|)
X2 = P(R).P(Noio = Nongthon|R).P(Diemvao = thap|R).
P(Kinhte = trungbinh|R). P(Gioitinh = Nam|R)
16
Ta ln lt tnh xc sut ca cc thuc tnh sau:
Ni
P(Thnh th| ) =3/5 P(Thnh th| R) =1/3
P(Nng thn| ) =2/5 P(Nng thn| R) =2/3
im vo
P(Cao| ) =2/5 P(Cao| R) =0/3
P(Trung bnh| )=3/5 P(Trung bnh| R)=1/3
P(Thp| ) =0/5 P(Thp| R) =2/3
Kinh t
P(Cao| ) =3/5 P(Cao| R) =0/3
P(Trung bnh| )=2/5 P(Trung bnh| R)=1/3
P(Thp| ) =0/5 P(Thp| R) =2/3
Gtinh
P(Nam| ) =2/5 P(Nam| R) =2/3
P(N| ) =3/5 P(N| R) =1/3
17
Bc 2: Phn lp cho mu mi
X
Vy X1(lp ) = 5/8*2/5*0/5*2/5*2/5 = 0
X2(lp R) = 3/8*2/3*1/3*1/3*2/3 = 0.0123
CNB = max (X1(lp ) ; X2(lp R)) = X2(lp R)
X thuc lp Rt ngha l vi sinh vin sng Nng thn , im
vo thp, kinh t gia nh l Trung bnh v gii tnh l nam
th kt qu l Rt.
18
Mt s u im ca phng php Naive Bayes
Tnh xc sut r rng cho cc gi nh.
Kt hp nhiu d on ca nhiu gi nh.
Cc thuc tnh trong tp mu hc phi c lp vi iu kin.
chnh xc thut ton phn lp ph thuc nhiu vo tp
d liu hc ban u.
19
PHN TCH HI QUY
20
Khi nim phn tch hi qui
Phn tch hi quy l tm mi quan h ph thuc ca mt bin,
c gi l bin ph thuc vo mt hoc nhiu bin khc.
V d
Khi chng ta c gng gii thch tiu dng ca mi ngi,
chng ta c th s dng bin gii thch l thu nhp v tui.
21
M hnh hi quy n
Phng trnh hi quy n bin (ng thng) c dng tng qut:
Y=a+bX
Trong :
Y: l bin s ph thuc;
X: l bin s c lp;
a: l tung gc hay nt chn;
b: dc hay h s gc.
22
M hnh hi qui tuyn tnh a bin
M hnh hi qui tuyn tnh nhiu chiu c dng :
Y = + 1X1 + 2 X2 + + Xk + U
Y (bin ph thuc): ch tiu phn tch
( bin c lp): h s chn.
: h s c lng.
Xi cc yu t nh hng n nng sut.Vi i chy t 1 n k.
U l sai s
23
D ON KT QU HC TP
DA VO L THUYT
PHN LP NAIVE BAYES
24
Bi ton
Da vo thng tin d liu u vo l:
im trung bnh ca cc hc k
Thng tin c nhn: Ni , gii tnh, kinh t gia nh
D on kt qu cui cng ca sinh vin s t c trong
qu trnh o to.
25
Xy dng chng trnh d on
Phn 1: Thu thp thng tin cn thit ca sinh vin
Phn 2: Thc hin d on kt qu hc tp
Bc 1:
Kim tra thng tin u vo
Trng b hun luyn th s cho ra ngay kt qu
d on.
Bc 2:
Dng thut ton phn lp Naive Bayes d
on.
26
Chng trnh thc nghim
27
Trang 1: Trang ch, th hin thng tin hnh nh ca trng
Trang 2: D on kt qu hc tp
28
Trang 3: Nhp lut
29
Kt qu thc nghim
D on kt qu hc tp cui cng ca mnh trong sut qu
trnh hc t s c l trnh hc tt hn.
B hun luyn mu cn t do xc sut d on kt qu
cng b nh hng.
Hng pht trin
Th nghim chng trnh v xy dng b hun luyn mu
vi d liu u l im cc mn hc ca hc k trc d
on kt qu ca hc k sau.
30
Ti liu tham kho
[1] Hong Th Lan Giao, Giang Ho Cn (2011) - Nghin cu
ng dng thut ton phn lp vo bi ton d on ri ro tn
dng trong ngn hng v cc t chc tn dng - Mt s vn
chn lc ca Cng ngh thng tin v truyn thng, Cn
Th, 7-8 thng 10 nm 2011.
[2] Nguyn Vn Huy (2009)- Thut ton Bayes v ng dng -
Kha lun tt nghip i hc chnh quy ngnh CNTT.
[3] H h tr ra quyt nh
http://idoc.vn/tai-lieu/he-ho-tro-ra-quyet-dinh.html
[4] Bi ging Khai ph d liu, trng i hc Hng Hi (2011)
http://www.ebook.edu.vn/?page=1.37&view=22169
[5] Tm hiu v lut kt hp trong khai ph d liu
http://baigiang.violet.vn/present/same/entry_id/3541561
31
XIN CHN THNH CM N
QU THY C V CC BN
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