| You can type the first two letters of the variable name,
| then hit the Tab key (possibly more than once). Most
| programming environments will provide a list of variables
| that you've created that begin with 'my'. This is called
| auto-completion and can be quite handy when you have many
| variables in your workspace. Give it a try. (If
| auto-completion doesn't work for you, just type my_div and
| press Enter.)
> my_div
[1] 3.478505 3.181981 2.146460| Delete the 'testdir' directory that you just left (and everything
| in it)
> unlink("testdir", recursive = TRUE)| Finally, let's say that rather than repeating the vector (0, 1, 2)
| over and over again, we want our vector to contain 10 zeros, then
| 10 ones, then 10 twos. We can do this with the `each` argument. Try
| rep(c(0, 1, 2), each = 10).
> rep(c(0, 1, 2), each = 10)
[1] 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2what is the output of v1 + v2?
[1] 7 24 6
Warning message:
In v1 + v2 :
longer object length is not a multiple of shorter object lengthwhat is the output of v1 + v3?
[1] 3 6 5 8 7 10what is the output of v2 + v3?
[1] 3 6 5 8 7 10Explain the differences in these answers in relation to error warnings, and unexpected behavior in R
v1 + v2 gave a warning message that the longer object length was not a multiple of the shorter object length, so each number of v1 was not added an even number of times to the numbers of v2. Since the others added evenly, this message did not appear
Make a vector ‘v4’ of: eight, five, nine, one, negative three, zero, and twelve
use indexing and the sum() function to add the second, fourth, and seventh entry in v4
> sum(v4[2], v4[4], v4[7])
[1] 18combine indexing with the sum() function to add the second, fourth and seventh entry in v4
> sum(v4[2], v4[4], v4[7])
[1] 18sample at random, two elements v4 [hint, use the sample() function]
> sample(v4, 2)
[1] 9 1Use R to generate a vector of all integers between 6 and 10
using the colon operator
> v5 <- 6:10using the seq function
> v6 <- seq(6,10)Use the rep function in R to generate a vector with all integers between 6 and 10 repeated four times
Cycling through 6, 7, 8, 9 ,and 10
> rep(v5, 4)
[1] 6 7 8 9 10 6 7 8 9 10 6 7 8 9 10 6 7 8 9 10First repeating 6 four times, then repeating 7 four times, etc..
> rep(v5, each=4)
[1] 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9 10 10 10 10‘Identify whether the following variables are numerical or categorical. If numerical, state whether the variable is discrete or continuous. If categorical, state whether the categories have a natural order (ordinal) or not, (nominal)’. Answer with reference to the variable [i.e. The height of this building is a continuous, numerical variable].
The number of sexual partners in a year is a discrete, numerical variable
Petal area of rose flowers is a continuous, numerical variable
The number of heartbeats per minute of a Tour de France cyclist, averaged over the duration of the race is a discrete, numerical variable
Birth weight is a continuous numerical variable
Stage of fruit ripeness is a categorical variable with ordinal categories
Angle of flower orientation relative to the position of the sun is a continuous, numerical variable
Tree species is a categorical variable with nominal categories
Year of birth is a discrete numerical category
Gender is a categorical variable with nominal categories
The main problem here is sampling bias. They should have reinforced the cockpit.
The two variables are leaf type and number of leaves removed. Leaf type is a categorical variable and is the explanatory variable here and the number of leaves removed is numerical and is the response variable here.
These are the leaves that were removed, not a random sample of the total population of leaves, but specifically those that were removed.
This would effect the accuracy of the estimate.
The individual ants were randomly sampled in this experiment.