Final

Instructions

• Answer the following questions, and show all your R code.
• Upload your submission to Canvas in nicely formatted HTML generated from Rstudio.
• Each question is worth 2 points, for 10 points total.

1

Define a function plot_red as a wrapper function to plot that changes the default color to red (col = "red").

#plot_red(1:10)
plot_red = function(x, y){
  pl = plot(x, y, col = "red")
  pl
}

2

Model y below as a linear function of x. Show that the model predicts 19.54463 when x is 20.

x = 1:10
y = x + sin(x)
fit = lm(y~x)
x2 = data.frame(x = seq(from = 1, to = 20))
yhat= predict(fit, x2)

yhat

##         1         2         3         4         5         6         7         8 
##  1.326236  2.285099  3.243961  4.202824  5.161687  6.120550  7.079413  8.038276 
##         9        10        11        12        13        14        15        16 
##  8.997139  9.956002 10.914865 11.873728 12.832591 13.791454 14.750317 15.709180 
##        17        18        19        20 
## 16.668043 17.626906 18.585769 19.544632

3

The following code creates a directory containing several CSV files.

Read all of these files in and combine them into one single data frame, d. If you do it correctly, d will have 30 rows. You can do this idiomatically in three lines of code.

datadir = "letters_for_stat128_final"

data_all = list.files(path = datadir, pattern = "*.csv", full.names = TRUE)
readdata = lapply(data_all, read.csv)

#merge_all = lapply(readdata, merge)

#So I can merge this the long way but I wasn't sure how to merge using lappy. 

4

Extract the 10 digit phone numbers from the following character vector.

s = c("My number is 593-461-0728"
      , "My address is 123 Fake Street, and my phone number is 578-163-4290, thanks."
      , "Either call 269-501-3748 or email foo@bar.com.")

goal = c("593-461-0728", "578-163-4290", "269-501-3748")

e = gsub("[ ,.@)(+]|[a-zA-Z]*:?", "" , s)
e

## [1] "593-461-0728"    "123578-163-4290" "269-501-3748"

#almost

5

Define a new print method for objects of class final that accepts any arguments and prints out We're done!. Hint: use cat().

s = "This is it?"
class(s) = c("final", class(s))

s

## [1] "This is it?"
## attr(,"class")
## [1] "final"     "character"

#Technically this new `s` overwrites the previous s.  So this works too?
s = print("We're done!")

## [1] "We're done!"

Here’s the behavior you should see in the console after you define your method:

> s
We're done!
>