Answer the following by constructing appropriate R commands and/or giving a text narrative.
Show that names with different capitalization refer to different objects.
age = 21
Age = "The 21st century"
age
## [1] 21
Age
## [1] "The 21st century"
Age and age are different.
The name of the object being assigned to always goes to the left of the = operator. What happens if you put it on the right?
Show that a string and a name are different.
A is a string. B is a name.
A = "Hello."
B = 21 * 16
A
## [1] "Hello."
B
## [1] 336
Assign a string value to an object.
M = "What time is it?"
M
## [1] "What time is it?"
Use scientific notation to create these numbers: 100, 10, 0.001, 0.001
100
## [1] 100
10
## [1] 10
0.01
## [1] 0.01
0.001
## [1] 0.001
Try these mathematical operations and explain what the values mean:
1/0
## [1] Inf
0/0
## [1] NaN
sqrt(-3)
## Warning: NaNs produced
## [1] NaN
What's the difference between NaN and NA?
NaN means Not a Number. NA is an error you get when there are missing expressions in a command.
Show that the order of unnamed arguments makes a difference. Use seq() to illustrate this.
seq(11, 1)
## [1] 11 10 9 8 7 6 5 4 3 2 1
seq(1, 11)
## [1] 1 2 3 4 5 6 7 8 9 10 11
Find the names of the arguments to seq(). Show that when you use the names, the order doesn't matter.
seq(from = 1, to = 11)
## [1] 1 2 3 4 5 6 7 8 9 10 11
seq(to = 11, from = 1)
## [1] 1 2 3 4 5 6 7 8 9 10 11
What kind of object is created by date()?
date() produces a timestamp as shown
date()
## [1] "Tue Feb 26 22:11:23 2013"
Read in the data set “utilities.csv” with fetchData("utilities.csv")
How many rows are there?
What are the names of the variables?
ut = fetchData("utilities.csv")
## Retrieving from http://www.mosaic-web.org/go/datasets/utilities.csv
nrow(ut)
## [1] 99
names(ut)
## [1] "month" "day" "year" "temp"
## [5] "kwh" "ccf" "thermsPerDay" "dur"
## [9] "totalbill" "gasbill" "elecbill" "notes"
Write the Markdown to reproduce this outline. See below for a hint.
Hint:
### Fruits
1. Sweet
* Apples