Create item category constraints.

Create constraints related to item categories/groupings (as represented by itemCategories). That is, the created constraints assure that the number of items of each category per test form is either (a) smaller or equal than (operator = "<="), (b) equal to (operator = "="), or (c) greater than or equal to (operator = ">=") the corresponding targetValues.

Usage

itemCategoryConstraint(
  nForms,
  itemCategories,
  operator = c("<=", "=", ">="),
  targetValues,
  whichForms = seq_len(nForms),
  info_text = NULL,
  itemIDs = names(itemCategories)
)

Arguments

nForms

Number of forms to be created.

itemCategories

a factor representing the categories/grouping of the items

operator

A character indicating which operator should be used in the constraints, with three possible values: "<=", "=", or ">=". See details for more information.

targetValues

an integer vector representing the target number per category. The order of the target values should correspond with the order of the levels of the factor in itemCategory.

whichForms

An integer vector indicating which test forms should be constrained. Defaults to all the test forms.

info_text

a character string of length 1, to be used in the "info"-attribute of the resulting constraint-object.

itemIDs

a character vector of item IDs in correct ordering, or NULL.

Value

A object of class "constraint".

Examples

## constraints to make sure that there are at least 3 items of each item type
## in each test form
nItems <- 30
item_type <- factor(sample(1:3, size = nItems, replace = TRUE))
itemCategoryConstraint(2, item_type, ">=", targetValues = c(1, 3, 2))
#> Warning: Argument 'itemIDs' is missing. 'itemIDs' will be generated automatically.
#> Warning: Argument 'itemIDs' is missing. 'itemIDs' will be generated automatically.
#> Warning: Argument 'itemIDs' is missing. 'itemIDs' will be generated automatically.
#> $A_binary
#> 6 x 60 sparse Matrix of class "dgCMatrix"
#>                                                                               
#> [1,] 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 0 0 1 0 0 0 0 0 0 . . . . . . .
#> [2,] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 1 0 0 0 0 0
#> [3,] 1 0 1 0 0 0 0 0 0 1 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 0 0 . . . . . . .
#> [4,] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 1 0 0 0 0
#> [5,] 0 0 0 1 1 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 1 . . . . . . .
#> [6,] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 0 1 1 1 1
#>                                                   
#> [1,] . . . . . . . . . . . . . . . . . . . . . . .
#> [2,] 1 0 0 0 1 1 0 0 0 0 1 0 1 0 0 0 1 0 0 0 0 0 0
#> [3,] . . . . . . . . . . . . . . . . . . . . . . .
#> [4,] 0 0 1 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 0 0
#> [5,] . . . . . . . . . . . . . . . . . . . . . . .
#> [6,] 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 1
#> 
#> $A_real
#> NULL
#> 
#> $operators
#> [1] ">=" ">=" ">=" ">=" ">=" ">="
#> 
#> $d
#> [1] 1 1 3 3 2 2
#> 
#> $c_binary
#> NULL
#> 
#> $c_real
#> NULL
#> 
#> attr(,"class")
#> [1] "constraint"
#> attr(,"nForms")
#> [1] 2
#> attr(,"nItems")
#> [1] 30
#> attr(,"info")
#>   rowNr formNr itemNr   constraint
#> 1     1      1     NA item_type>=1
#> 2     2      2     NA item_type>=1
#> 3     3      1     NA item_type>=3
#> 4     4      2     NA item_type>=3
#> 5     5      1     NA item_type>=2
#> 6     6      2     NA item_type>=2
#> attr(,"itemIDs")
#>  [1] "it01" "it02" "it03" "it04" "it05" "it06" "it07" "it08" "it09" "it10"
#> [11] "it11" "it12" "it13" "it14" "it15" "it16" "it17" "it18" "it19" "it20"
#> [21] "it21" "it22" "it23" "it24" "it25" "it26" "it27" "it28" "it29" "it30"