outline - stanford universitycs229.stanford.edu/livenotes2020spring/cs229-livenotes... · 2020. 4....
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OutlineNaive BayesLaplace smoothingEvent models
comments on applied ML
kernel Methods
Recap
XEaby
X I word appears on email
Generative Model
PCxly p yp Hy ITp xilyParameters P y D yP X L I y 0 Oily 0P X II y L lo ly L
Max likelihood estimates
y I I y 13T
lo'sly o Eh I xj L y o
I gil 03l l
s ly I
At prediction time
peg Ha pcxty D pcy.snopCx1yD.PCy D PCX1y o3 PCy o 0
Near IPSj 5500
P 45500 1 9 1g0 05500151
P X5500 11 y 0 g0 05500 ly O
paly D IIEpcxjly.IM 9Tooly1PCx1yo jFI pcxs1y o o55ooly L
Laplace smoothing2009
412 WakeforestWoon
1010 OSU O10117 Arizona O11 21 Caltech O12 31 Oklahoma 0
PEX L IIst o's 2
L I0 4 60 Ig
Laplace Smoothing has IO's c I
More generally XEEL K
Estimate 2 xin j I
PCx j I
Qjly o IE IE L g 03 I P Xg L g o
I y 0 t 2 pasty o
Xi C I Kthx 019 4 1
SIZE 4010feet 4002800
80031200
71200X 4
PCxly ftp.pcx.lyMultinomial Cvs bernoulli
Is P X 1 P D L
PCXg4y o tPCXg oly o I
Ig1 bank
beneficiary
XiE 0,1
account bank account800 1600 800
E IRD di lengthof email i
Xj C I 10,0003
So far Multivariate Bernoulli event modelNew Multinomial event model
Generative model
PCx y paly peg
paly II P x Lg
Parameters
y My L
4k1g o P X k ly o
Chanceofwordj bang k f g 0
Assume that this does not depend on j10Kly I P X k ly L
MLE01k1g so 2 I yakoy 7 I x Ky L
E I y o de 10,000
Laplacesmoothing
Xj of jeh worden emailptosetcon in the dictionary
P
map fare wordstoUNLa
mortgage mafrtgageIUNK
0k1g I P yahword k ly L
independent of j
PCxly II p x lysq
PCH1197 PCH 01g Pas Ily
PCHg III palslyk 4 sum
linear f tquadratic fcubicfh of data
ho X Oo 10 X t 02 4 03 3
01cmng 4 IR IN
holm Coo O 0297beg
tote
sea y X yI
Cx y Colin y
Recall linear regression0 0
opoi o d.IECy otx x
t tRd scalar IRd
New dataset0 0Loop
oi q x.E.cya q EY.MEIRP IRPscalar
4 Rd IRP d L p 4 in example
Terminologyfeaturemap
0cal Chew featurere attributes
kernel methods
d L X Xi XD
Glx ft
OT a can represent anyxD Jd degree3 poly in Xi Xd
1es
lid3XdXdXd
time per iteration ocnp pndImprove this to 0cm per iteration
Even storing 0 takes time Ocp
p n