Query the built-in mtcars dataset

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George Stagg

said

Needs to be tested

3 years, 1 month ago

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Christian Lawson-Perfect 1 year, 10 months ago

Published this.

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George Stagg 3 years, 1 month ago

Gave some feedback: Needs to be tested

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George Stagg 3 years, 1 month ago

Created this.

Name	Status	Author	Last Modified
Query the built-in mtcars dataset	Needs to be tested	George Stagg	10/05/2023 13:34
Query the built-in mtcars dataset	Ready to use	Christian Lawson-Perfect	23/11/2023 12:24

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Question statement

The Motor Trend Car Road Tests data frame is built into R with the variable name mtcars.

Before answering this question, first get a feel for the structure of the dataset by using commands such as head(mtcars) and help(mtcars).

Give any introductory information the student needs.

			Name	Type	Generated Value

num_gears	integer	4
disp_val	integer	340
num_cyl	integer	4
part_a_answer	string	gears = mtcars[mtcars$gear ==
part_b_answer	string	displ = mtcars[mtcars$disp>300
part_c_answer	string	mercs = mtcars[grep('Merc', ro
part_d_code	string	max(mtcars$hp)
part_e_code	string	mean(mtcars[mtcars$cyl == 8,]$
part_f_code	string	as.numeric(quantile(mtcars[mtc

Automatically regenerate variables?

Name

Data type

Value

xxxxxxxxxx
 
random(3..5)

JME function reference

Description

Describe what this variable represents, and list any assumptions made about its value.

Can an exam override the value of this variable?

Generated value: `integer`

This variable doesn't seem to be used anywhere.

Code

Ask the student a question, and give any hints about how they should answer this part.

Write an R command to create new data frame named gears that contains only the cars with {num_gears} gears.

Help with this part type

Marks

Show correct answer on reveal?

Show score feedback icon?

Show the input hint?

Code language

The language that the student's code will be written in.

Correct answer

xxxxxxxxxx
 
{part_a_answer}

A correct answer to the part.

Substitute question variables into the correct answer?

If ticked, then JME expressions between curly braces will be evaluated and substituted into the correct answer.

If not ticked, then the correct answer will be displayed exactly as it is.

Show stdout?

If ticked, the STDOUT produced after running the student's code will be shown in the feedback.

Show stderr?

If ticked, the STDERR produced after running the student's code will be shown in the feedback.

Show errors produced by marking tests?

Placeholder

xxxxxxxxxx
 
gears = 

Initial text for the code editor

Student code modifier

​x
 
​

JME expression to modify the student's submitted code before being passed to the marking template. The student's code is available as the string variable studentAnswer.

Preamble

​

This code is run before the student's code. Define anything that the student's code or your tests need.

Postamble

​

This code is run after the student's code but before the validation and unit tests.

Format postamble output as code?

If ticked, any output produced by the postamble will be formatted in monospace font, with whitespace preserved. If not ticked, it'll be presented as prose text or HTML.

Marking tests

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[
  ["Correct data frame", 1, "identical(gears, mtcars[mtcars$gear == num_gears,])"]
]

A list of tests used to mark the student's answer.
Each item is a list with three values:

The name of the test, shown to the student above any feedback.
The proportion of the credit available for the part to award if this test is passed.
The code to run.

Validation tests

xxxxxxxxxx
 
[
  ["Data frame 'gears' exists", "exists('gears')"]
]

A list of tests used to validate that the student's code is acceptable.
Each item is a list with two string values:

A name which will be shown to the student if the test fails.
The code to run.

Variables to include in code

xxxxxxxxxx
 
['num_gears': num_gears]

Give a dictionary mapping variable names to their values. These variables will be available in the code that is run.

Advice

a)

{code_block(part_a_answer,"r")}

b)

{code_block(part_b_answer,"r")}

c)

{code_block(part_c_answer,"r")}

d)

To calculate the maximum horsepower, run

{code_block(part_d_code,"r")}

e)

To calculate the mean mpg of cars with 8 cylinders, run

{code_block(part_e_code,"r")}

f)

To calculate the 75% quantile, run

{code_block(part_f_code,"r")}

Give a worked solution to the whole question.

Use this tab to check that this question works as expected.

There was an error which means the tests can't run:

Part	Test	Passed?
Code
Code		Hasn't run yet
Code
Code		Hasn't run yet
Code
Code		Hasn't run yet
Number entry
Number entry		Hasn't run yet
Number entry
Number entry		Hasn't run yet
Number entry
Number entry		Hasn't run yet

This question is used in the following exam:

Programming extension demo by Christian Lawson-Perfect in Programming extension.

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Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

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Checkpoint description

Christian Lawson-Perfect 1 year, 10 months ago

George Stagg 3 years, 1 month ago

George Stagg 3 years, 1 month ago

Error in variable testing condition

Error

Warning

Generated value: `integer`

Parts

Code

a)

b)

c)

d)

e)

f)

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Error

Query the built-in mtcars dataset

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

Christian Lawson-Perfect 1 year, 10 months ago

George Stagg 3 years, 1 month ago

George Stagg 3 years, 1 month ago

Error in variable testing condition

Error

Warning

Generated value: integer

Parts

Code

a)

b)

c)

d)

e)

f)

Generated value: `integer`