Extracts contained objects by name or position without modifying the comparison or copying its objects. A single selection returns the object itself by default.
Arguments
- x
A
TrialComparison.- ...
Object names or integer positions, including vectors and multiple selections. Names may be quoted or unquoted. Positive positions count from the beginning and negative positions from the end. With no selection, the last object is returned. Quasi-quotation and programmatic selectors are supported; an unquoted name matching a contained object takes precedence over a variable of the same name in the calling environment.
- output
One of "value" (default), "named", "labeled", or "list". "value" returns a single selected object directly and multiple selections as a named list. The other modes always return a named list. Collection labels are the supplied object names, with positions for unnamed objects; consequently "labeled" and "named" are equivalent for comparisons.
Value
A contained object by reference or a list of objects. An unknown name returns NULL (retained as a NULL entry in list output). Empty selector vectors return an empty list.
Details
fetch(x, "fixed"), fetch(x, fixed) and fetch(x, 1) provide the named and
positional object access supported by [[. Only contained objects are selected;
R6 members are never returned as a fallback. Numeric positions must be finite,
nonzero integers within the collection bounds. Selecting the last object of
an empty comparison raises an index error.
See also
fetch() and getComparison().
Examples
comparison <- getComparison(fixed = getDesignFixed(),
sequential = getDesignGroupSequential(kMax = 2))
identical(comparison |> fetch("fixed"), comparison[["fixed"]])
#> [1] TRUE
identical(comparison |> fetch(fixed), comparison$fixed)
#> [1] TRUE
identical(comparison |> fetch(1), comparison[[1]])
#> [1] TRUE
comparison |> fetch(-1)
#> Design parameters and output of group sequential design:
#>
#> User defined parameters:
#> Maximum number of stages : 2
#> Stages : 1, 2
#>
#> Default parameters:
#> Type of design : O'Brien & Fleming
#> Significance level : 0.0250
#> Type II error rate : 0.2000
#> Binding futility : FALSE
#> Test : one-sided
#> Tolerance : 1e-08
#>
#> Derived parameters:
#> Information rates : 0.500, 1.000
#> Futility bounds (non-binding) : -Inf
#>
#> Output:
#> Cumulative alpha spending : 0.002583, 0.025000
#> Critical values : 2.797, 1.977
#> Stage levels (one-sided) : 0.002583, 0.023996
#>
comparison |> fetch(1:2, output = "list")
#> $fixed
#> Design parameters and output of fixed sample size design:
#>
#> User defined parameters: not available
#>
#> Default parameters:
#> Significance level : 0.0250
#> Type II error rate : 0.2000
#> Test : one-sided
#>
#> Output:
#> Critical values : 1.960
#> Stage levels (one-sided) : 0.0250
#>
#>
#> $sequential
#> Design parameters and output of group sequential design:
#>
#> User defined parameters:
#> Maximum number of stages : 2
#> Stages : 1, 2
#>
#> Default parameters:
#> Type of design : O'Brien & Fleming
#> Significance level : 0.0250
#> Type II error rate : 0.2000
#> Binding futility : FALSE
#> Test : one-sided
#> Tolerance : 1e-08
#>
#> Derived parameters:
#> Information rates : 0.500, 1.000
#> Futility bounds (non-binding) : -Inf
#>
#> Output:
#> Cumulative alpha spending : 0.002583, 0.025000
#> Critical values : 2.797, 1.977
#> Stage levels (one-sided) : 0.002583, 0.023996
#>
#>