原则人工智能用于人工智能的Python

copyrightPaulaMatuszek2017

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CMSC671:Principlesof

ArtificialIntelligencePythonforAI

Dr.PaulaMatuszek

Paula.Matuszek@

Paula.Matuszek@

(610)647-9789

WhyPythonforAI?

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ThetraditionalAIlanguagesareLispandProlog

WhenperformanceisaseriousissuecommonlyusedlanguagesincludeC++,sometimesJava,andmorerecentlyGPU-basedlanguages

SowhyPython?

Lightweightstartup,interpreter,IDLE.

Object-oriented

Usefulbuilt-indatastructuresandoperationsforsymbolicprocessing:dictionaries,lists,sets,strings

Strongnumericprocessingforstatisticalprocessing:matrixoperations,etc.

PythonforAI

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Inadditiontothebuilt-incapabilities,Pythongetsmuchofitspowerfromlibrariesthatcanbeimportedtoaddcapabilities

Acoupleofbasiconesyouwillwant(andprobablyhave)

NumPy:mathfunctionsforforarraysandmatrices

matplotlib:plottinglibraryforPythonandNumPy.

PooleandMackworthhavealargesetofPythontoolswhichimplementmanybasicAIfunctions.Theyarestartingpoints,notpolishedcode.

/AIPython/

ThePDF

/AIPython/aipython.pdf

givesadiscussionofPythonandofthetools.

MoreSpecificAILibraries

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Asyougetintomoreadvancedtopics,forprojectsorlaterinthecourse,youwillreachsomeareaswhereyoudon’twanttoimplementfromscratch.Thereareanumberof

morespecificlibrariesthatletyouconcentrateonabroaderproblem.

Someofthebest-knownare

NaturalLanguageToolkit(NLTK)

Scikit-learn

TensofFlow

NLTK

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WhatisNLTK?

NaturalLanguageToolKit

SetofmodulesforPython

Largenumberoftoolsforprocessingnaturaltext

Alargestofrelevantdata

Widelyusedfornaturallanguagerecognition,speechprocessing,textmining,speechtranslation.

Startingpointis

/.

SomeNLTKModules

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NLTKisatoolkitforprocessingtext

Textistreatedasalistofwords

Modulesinclude

Stemmers,Tokenizers,Parsers

PartofSpeechandNamedEntityTaggers

N-Grams,FrequencyDistributions,otherstatistical

Classifyingdocumentsintopredefinedgroups

Clusteringdocumentsintogroups

NLTKCorpora

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NLTKalsohasalargesetofcorpora:existingtextbodiesthatcanreadilybeprocessed.

Brown:About500Englishdocuments,aboutamillionwords,compiledfromavarietyofsources.Firstgeneralcomputercorpusavailable.

Reuters:about800,000newsarticles

Gutenberg:18worksfrom12authors

Shakespeare:8ofhisplays

Currentlistat

/nltk_data/

Italsoincludesdictionaries,gazetteers,trainedmodels.

Example

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Simpleclassifier,tryingtoclassifynamesintomaleandfemalebythelastletter.

/~matuszek/fall2013/

Sep11Classify.py

Scikit-learn

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SciPyis“aPython-basedecosystemofopen-sourcesoftwareformathematics,science,andengineering.”(https://

/)]

NumPyandmatplotlibarefromhere.

Scikit-learnisasetofmachinelearningmodulesbuiltontopofSciPy.(

/stable/)

Scikit-learnmodules

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Scikit-learnmodulesaregroupedintosixkinds:

Classification

Regression

Clustering

DimensionalityReduction

DataPreparation

ModelSelection

Classification

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Decidingwhatgroiponclassanobjectbelongsto

Algorithms:

DecisionTrees

KNearestNeighbor

NaiveBayes

SupportVectorMachones

Examples:malevsfemale:-).Spamdetection,loanapplications,collegeadmissions,imageidentification

Regression

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Predictingacontinuousvalue(ratherthanaclass)foranobject

Algorithms

Leastsquareslinearregression

LogisticRegression

Examples:whichwillthishousesellfor?WhatGPAcanweexpectthisstudenttoachieve?Whattemperaturewillitbetomorrow?

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Clustering:groupingsimilarobjectswithoutanyaprioridefinitionofgroups

Algorithms:

K-Means

Agglomerativeclustering

Hierarchicalclustering

Examples:whatarethenewstopicsinthesearticles?HowmanydifferentthingsdoIhaveimagesof?Whatarethekindsofcallstothehelpdeskwearegetting?

DimensionalityReduction

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Reducingthetotalnumberofvariablesforeachindividualwithoutlosingexplanatorypower

Algorithms

PrincipalComponentAnalysis

FactorAnalysis

SingularValueDecomposition

Examples.Reducingtextvectorlengths,eliminatingsomeoftheredundancyinnaturallanguage.Reducingimagevectors,eliminatingirrelevantvariationfromlighting.

TheRest

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Preprocessing.Datacleanup

Algorithms:featureextractionandnormalization

Examples:Usingweightandheightinthesameclassification,turninga10-pointmovieratinginto“yes,no”.

ModelSelection.Checkingusefulnessofmodels,comparingdifferentapproachesandparameters.

Examples:Eachoftheabovemethodsproducesamathematicalmodelorformulawhichcanthenbeappliedtonewdata.Andeachhasmanyparameterswhichcanbetweaked.Thesetools

helpdecideamongtheoptionsanddeterminewhethertheyareactuallygood.

Allofthisiswelldocumentedatthescikit-learnsite.

Andothers

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TensorFlowisGoogle’sdeeplearningframework;itiswrittenmostlyinC++,buttheAPIisPythonbased.It’srelativelynew,notaswid