moreR_4perPage - More Classification in R Data Mining Prof....

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Unformatted text preview: More Classification in R Data Mining Prof. Dawn Woodard School of ORIE Cornell University 1 Outline 1 Announcements 2 Workspaces 3 Writing Functions and Loops 4 Homework 2 Announcements ... 4 R Workspace The objects currently in the workspace can be listed using the ls() command You can remove an object by calling e.g. remove( a ) I like to clear the workspace occasionally so that I do not mistakenly refer to the wrong object > remove( list=ls() ) 6 Homework due Tuesday Part I: You will need to write a function to predict based on your classification tree Part II: You will improve your classification rule 8 Functions in R Define a simple function: myFun <- function(a) { print( sum(a) ) return( mean(a) ) } Call your function. Whats the result? b <- myFun( (1:4) ) b 9 Functions in R A functions scope means the set of objects that you can refer to inside the function. myFun <- function(a) { print( sum(a) ) return( mean(a) ) } What is the scope of myFun? 10 Functions in R Unfortunately in R, inside a function it is possible to refer to objects that are not arguments to that function > b <- 2 > myFun <- function() { b } > myFun() [1] 2 I do NOT want you to do this It can cause terrible bugs 11 Nested Functions Functions can call other functions: myFun1 <- function(c) { return( c+2 ) } myFun2 <- function(a) { print( sum(a) ) d <- myFun1( a )...
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This note was uploaded on 12/23/2009 for the course ORIE 4740 at Cornell University (Engineering School).

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moreR_4perPage - More Classification in R Data Mining Prof....

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