R vectors

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From users who are members of R programming :

Aamir Khan

said

Needs to be tested

2 years, 10 months ago

From users who are not members of R programming :

Christian Lawson-Perfect

said

Has some problems

3 years ago

History

○

Christian Lawson-Perfect 1 year, 10 months ago

Published this.

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Aamir Khan 2 years, 10 months ago

Gave some feedback: Needs to be tested

○

Aamir Khan commented 2 years, 10 months ago

Added an alternative answer for part d to detect a logical vector.

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Aamir Khan 3 years ago

Gave some feedback: Ready to use

○

Aamir Khan commented 3 years ago

Added randomisation to part b to avoid literal values being marked as correct.

Leaving alternatives for now as it seems broken.

○

Christian Lawson-Perfect 3 years ago

Gave some feedback: Has some problems

○

Christian Lawson-Perfect commented 3 years ago

In parts b and d, I'd randomise the values of x and y, so you can't just write down the literal values given in the prompts.

This might be going over and above, but in part d if I answer z <- y>55, I get a vector of booleans. Could you detect that with an alternative?

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Aamir Khan commented 3 years, 1 month ago

Updated to new extension.

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Aamir Khan 3 years, 1 month ago

Gave some feedback: Needs to be tested

○

Aamir Khan 3 years, 1 month ago

Saved a checkpoint:

Checkpoint before new extension

Restore this checkpoint

○

Aamir Khan 3 years, 5 months ago

Gave some feedback: Ready to use

○

Aamir Khan 3 years, 5 months ago

Created this as a copy of R vectors.

There is only one version of this question that you have access to.

There are 29 other versions that do you not have access to.

Question statement

Give any introductory information the student needs.

			Name	Type	Generated Value

x_vector	vector	vector(3,8,4,6,6,4,9,6)
x_r	string	3,8,4,6,6,4,9,6
partc_a	integer	3
partc_b	integer	104
partc_step	number	0.2
partb_n	integer	2
partd_n	integer	53
parte_a_a	integer	8
parte_a_b	integer	22
parte_a_length	integer	170
parte_b_a	integer	5
parte_b_b	integer	28

Automatically regenerate variables?

Name

Data type

Value

xxxxxxxxxx
 
vector(repeat(random(1..10),8))

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: `vector`

vector(3,8,4,6,6,4,9,6)

→ Used by:

"Part a)" - prompt

Parts

Part a) Code
Part b) Code
1. Alt Unnamed alternative
Part c) Code
Part d) Code
1. Alt Unnamed alternative
Part e) Code

Code

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

Give the command to define a vector x that contains the numbers {join(x_vector,',')}.

Help with this part type

Marks

Show correct answer on reveal?

Show score feedback icon?

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Code language

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

Correct answer

xxxxxxxxxx
 
x=c({x_r})

A correct answer to the part.

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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.

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

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Placeholder

​x
 
​

Initial text for the code editor

Student code modifier

​

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.

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​

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

xxxxxxxxxx
 
[
  ["Correct assignment", 1, "all(x==c({x_r}))&length(x)==8"]
]

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
 
[
  ["Make sure to assign to a variable <code>x</code>","exists('x')"]
]

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
 
dict('x_r':x_r)

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

Advice

a) To define a vector in R and assign it to a variable x we use the c function as follows:

x=c({x_r})

b) To access elements of a vector we use square brackets [] after the name of our vector:

x[{partb_n}]

c) We can also use the seq command to define a vector. Here we wish to define a vector y where the first element is $\var{partc_a}$ and the sequence increases by a step size of $\var{partc_step}$ up to $\var{partc_b}$ .

y=seq({partc_a},{partc_b},by={partc_step})

d) To select all of the elements of our vector y that are greater than $\var{partd_n}$ we again use square brackets around the logical expression we wish to evaluate:

z=y[y>{partd_n}]

e) To define the two vectors a and b we use the seq command but define the total length of the vector using length.out={parte_a_length} (instead of the step size as in part c). We can then apply component-by-component operations to vectors easily:

a=seq({parte_a_a},{parte_a_b},length.out={parte_a_length})
b=seq({parte_b_a},{parte_b_b},length.out={parte_a_length})
d=a+b
e=a*b

Give a worked solution to the whole question.

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This question is used in the following exams:

R Syntax by Aamir Khan in MAS8406.
Practice Material for Numbas Test 1 by Rachel Binks in NCL MAS2906.
Week 3 assessment by Aamir Khan in MAS8406.
R programming practice by Aamir Khan in R programming.
R Syntax by Aamir Khan in NCL PSY3048.
R Refresher Test by Aamir Khan in NCL MAS2906.
R Refresher Test by Chris Graham in Chris's workspace.

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Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

Christian Lawson-Perfect 1 year, 10 months ago

Aamir Khan 2 years, 10 months ago

Aamir Khan commented 2 years, 10 months ago

Aamir Khan 3 years ago

Aamir Khan commented 3 years ago

Christian Lawson-Perfect 3 years ago

Christian Lawson-Perfect commented 3 years ago

Aamir Khan commented 3 years, 1 month ago

Aamir Khan 3 years, 1 month ago

Aamir Khan 3 years, 1 month ago

Aamir Khan 3 years, 5 months ago

Aamir Khan 3 years, 5 months ago

Error in variable testing condition

Error

Warning

Generated value: `vector`

Parts

Code

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Error

R vectors

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

Christian Lawson-Perfect 1 year, 10 months ago

Aamir Khan 2 years, 10 months ago

Aamir Khan commented 2 years, 10 months ago

Aamir Khan 3 years ago

Aamir Khan commented 3 years ago

Christian Lawson-Perfect 3 years ago

Christian Lawson-Perfect commented 3 years ago

Aamir Khan commented 3 years, 1 month ago

Aamir Khan 3 years, 1 month ago

Aamir Khan 3 years, 1 month ago

Aamir Khan 3 years, 5 months ago

Aamir Khan 3 years, 5 months ago

Error in variable testing condition

Error

Warning

Generated value: vector

Parts

Code

Generated value: `vector`