First read Appendix B of the textbook Modern Data Science with R: http://mdsr-book.github.io.
The following exercises are taken from Appendix B.
A user has typed the following commands into the console.
obj1 <- 2:10
obj2 <- c(2, 5)
obj3 <- c(TRUE, FALSE)
obj4 <- 42
What values are returned by the following commands?
obj1 * 10
obj1[2:4]
obj1[-3]
obj1 + obj2
obj1 * obj3
obj1 + obj4
obj2 + obj3
sum(obj2)
sum(obj3)
SOLUTION:
A user has typed the following commands into the console.
a <- c(10, 15)
b <- c(TRUE, FALSE)
c <- c("happy", "sad")
What do each of the following commands return? Describe the class of the object as well as its value.
data.frame(a, b, c)
cbind(a, b)
rbind(a, b)
cbind(a, b, c)
list(a, b, c)[[2]]
SOLUTION:
A user has typed the following commands into the console.
mylist <- list(x1="sally", x2=42, x3=FALSE, x4=1:5)
What values do each of the following commands return?
is.list(mylist)
names(mylist)
length(mylist)
mylist[[2]]
mylist[["x1"]]
mylist$x2
length(mylist[["x4"]])
class(mylist)
typeof(mylist)
class(mylist[[4]])
typeof(mylist[[3]])
SOLUTION:
The following concepts should have some meaning to you: package, function, command, argument, assignment, object, object name, data frame, named argument, quoted character string. Construct an example of R commands that make use of at least four of these. Label which part of your example R command corresponds to each.
SOLUTION:
Which of these kinds of names should be wrapped with quotation marks when used in R? 1. function name 2. file name 3. the name of an argument in a named argument 4. object name
SOLUTION:
What’s wrong with this statement?
help(NHANES, package <- "NHANES")
Consult the documentation for CPS85
in the mosaicData
package to determine the meaning of CPS.
SOLUTION:
library(mosaicData)
# solution does here
For each of the following assignment statements, describe the error (or note why it does not generate an error).
result1 <- sqrt 10
result2 <-- "Hello to you!"
3result <- "Hello to you"
result4 <- "Hello to you
result5 <- date()
SOLUTION: