logo Use SA10RAM to get 10%* Discount.
Order Now logo

Ask This Question To Be Solved By Our ExpertsGet A+ Grade Solution Guaranteed

Chris AddisonCriminology

899 Answers

Hire Me
Fifi BoxNursing

919 Answers

Hire Me
Maurice FrancePsychology

598 Answers

Hire Me
Jeremy HardyEconomics

891 Answers

Hire Me
R Programming

Write a function base.function.most.methods() that returns a list with components base.function,


1 Least absolute deviations regression:  a lad() function


Your package will have a function lad(x, y) which takes as arguments vectors x and y and returns an object having the (new) class "lad" and consisting of a list with these components:


coefficients,  a  named  numeric  vector  of  length  2  containing  the  coefficients  (βˆ0, βˆ1)  of  a linear model and having the names "(Intercept)" and "x"

fitted.values, a vector of the {yˆi}

residuals, a vector of the {ei = yi − yˆi}

(The name “lad” stands for “least absolute deviations.” lad() will be a function somewhat like

lm(), which uses the usual “least squared deviations” regression.)

To  find  (βˆ0, βˆ1),  use  optim()  with  its  (default)  Nelder-Mead  algorithm  to  minimize  the  sum  of absolute deviations (SAD) of data yi from predictions yˆi.  That is, minimize



SAD(β0, β1) = SAD(β0, β1; →x, →y) = |yi − β0 − β1xi|



over (β0, β1). Use the least squares estimates from lm() as initial values.

Test your function by running


area = read.csv("http://www.stat.wisc.edu/~jgillett/305/2/farmLandArea.csv") lad(x=area$land, y=area$farm)


Make your function code general–we may test it on several data sets, so don’t write any dependence on "farmLandArea.csv" in lad().


2 Write an R package


Create a package robust containing:


the function lad(), described above

the data frame area (which should have no persisting dependence on "farmLandArea.csv")

the method print.lad(x, ...), which writes the named coefficients vector to the console

the method coef.lad(object, ...), which takes a lad object object and returns its vector of coefficients. (This will allow abline(reg) to work, where reg is a regression model object returned by lad(), making it easy to add a lad regression line to a scatterplot. See ?abline if you want more understanding of its reg parameter.)

the method predict.lad(object, new.x, ...), which takes a lad object object and a vector new.x and returns a vector containing lad’s predictions at the x values in new.x.


Each of these items should be documented so that R’s help via ? works for them. Document the

... parameter in each of the methods via

@param ... further arguments passed to or from other methods

(This “...” parameter is necessary to pass check() without warnings, and to make our new methods behave correctly in object oriented programming situations we didn’t discuss.)

After installing your package, when we run example(lad), it must


call your lad() function for the farmland dataset

use print() to print βˆ0  and βˆ1

make a scatterplot with the lm() line, the lad() line in a different color, and a legend

use predict() to find yˆ for x values corresponding to the 0, 1/4, 1/2, 3/4, and 1 quantiles of the data; add these five predictions as solid green points to the graph


Cautions: lad() should not produce a graph. Do not call print.lad(), coef.lad(), or predict.lad() directly: use print(), abline(), and predict() on your lad object.



3 Optional (for extra credit in the form of candy)


Include test code in your package. I recommend http://r-pkgs.had.co.nz/tests.html.

Write a function base.function.most.methods() that returns  a  list  with  components  base.function, the base R generic function having the most methods, and n, the number of its methods. Hint:

See ?base for how to list base functions, ?methods for how to list the methods of a generic function, and ?try for how to prevent errors produced by calling methods() on non-generic functions from terminating your function.


Related Questions

. The fundamental operations of create, read, update, and delete (CRUD) in either Python or Java

CS 340 Milestone One Guidelines and Rubric  Overview: For this assignment, you will implement the fundamental operations of create, read, update,

. Develop a program to emulate a purchase transaction at a retail store. This  program will have two classes, a LineItem class and a Transaction class

Retail Transaction Programming Project  Project Requirements:  Develop a program to emulate a purchase transaction at a retail store. This

. The following program contains five errors. Identify the errors and fix them

7COM1028   Secure Systems Programming   Referral Coursework: Secure

. Accepts the following from a user: Item Name Item Quantity Item Price Allows the user to create a file to store the sales receipt contents

Create a GUI program that:Accepts the following from a user:Item NameItem QuantityItem PriceAllows the user to create a file to store the sales receip

. The final project will encompass developing a web service using a software stack and implementing an industry-standard interface. Regardless of whether you choose to pursue application development goals as a pure developer or as a software engineer

CS 340 Final Project Guidelines and Rubric  Overview The final project will encompass developing a web service using a software stack and impleme

Get Free Quote!

380 Experts Online