grade.discreteprobability: Grade Discrete Probability Sets
In grade: Binary Grading functions for R.

Description Usage Arguments Details Value Note See Also Examples

View source: R/grade.discreteprobability.R

Checks a students probability distribution, makes sure that (1) It sums to 1 (2) All elements are >= 0

Optionally, it compares the students to a correct one. Order is optionally enforced.

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grade.discreteprobability(correctans, studentans, tolerance=.01,
                          useeval=TRUE, usena=FALSE, useinf=FALSE,
                          quiet=TRUE, ordered=FALSE, checkcorrect=TRUE)

`correctans`	a vector of type `numeric` or a `string`
`studentans`	a vector of type `numeric` or a `string`
`tolerance`	a `string` or `numeric` representing the accepted component wise tolerance
`useeval`	`TRUE` or `FALSE` indicates whether or not to use 'eval' on strings
`usena`	`TRUE` or `FALSE` indicating whether or not `NA` is an accepted value
`useinf`	`TRUE` or `FALSE` indicating whether or not `Inf` and `-Inf` are accepted values
`quiet`	`TRUE` or `FALSE`. If `TRUE` there are more warning messages when checks fail. Can be helpful for debugging.
`ordered`	`TRUE` or `FALSE`. If `TRUE` studentans order must match correctans order to be considered correct. If `FALSE`, order does not matter (so both are sorted and then checked)
`checkcorrect`	`TRUE` or `FALSE`. if `TRUE` studentans needs to match correctans. If `FALSE` studentans only needs to qualify as a discrete probability distribution.

If checkcorrect=FALSE, grade.discreteprobability does not do any checks on correctans. In this case to be correct, studentans needs to satisfy discrete probability constraints – all elements >= 0 and sums to 1.

If checkcorrect=TRUE discrete probability constraints are enforced on correctans. studentans needs to match correctans in this case. Order is only enforced if ordered=TRUE.

grade.discreteprobability does not use NA. If usena=TRUE grade.discreteprobability sets it to FALSE and issues a warning message.

TRUE or FALSE indicating match success or failure respectively. FALSE is also returned if studentans does not look like a set.

The grade main page contains a discussion of the common parameters correctans, studentans, useeval, usena, useinf, quiet.

grade grade.set

# TRUE
grade.discreteprobability(c(1/2,1/2), "[.5, .5]")
# TRUE
grade.discreteprobability(NULL, "[0, .33, .17, .5]", checkcorrect=FALSE) 

# FALSE
grade.discreteprobability(NULL, "[-1, 0, 0, 1, 1]", checkcorrect=FALSE)

# TRUE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, 1/2, 1/4, 1/4]")
# FALSE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, .25, .25, .5]",
                          ordered=TRUE)

# TRUE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, .5, .25, .25]",
                          ordered=TRUE)