Unit Contrast Weights

Compute the contrast weights for a unit_contrast_spec object.

Compute the contrast weights for an oneway_contrast_spec object.

Compute the contrast weights for an interaction_contrast_spec object.

Compute the contrast weights for a poly_contrast_spec object.

Compute the contrast weights for a pair_contrast_spec object.

Compute contrast weights for a column_contrast_spec object by targeting the term's design matrix columns with regex patterns. Patterns are matched against the design-matrix column names (term_tag_condition_tag[_b##]) first and, only if they match none, against the term-level condition names; see column_contrast() for the precedence rules.

Compute the contrast weights for a contrast_formula_spec object.

Compute the contrast weights for a contrast_diff_spec object.

Compute the contrast weights for each contrast specification within a contrast_set object.

Usage

# S3 method for class 'unit_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'oneway_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'interaction_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'poly_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'pair_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'column_contrast_spec'
contrast_weights(x, term, ...)

# S3 method for class 'contrast_formula_spec'
contrast_weights(x, term, ...)

# S3 method for class 'contrast_diff_spec'
contrast_weights(x, term, ...)

# S3 method for class 'contrast_set'
contrast_weights(x, term, ...)

contrast_weights(x, ...)

# S3 method for class 'convolved_term'
contrast_weights(x, ...)

# S3 method for class 'event_model'
contrast_weights(x, ...)

Arguments

x

The object.

term

A term object against which weights should be computed.

...

Additional arguments.

Value

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the contrast details:

term

The original event_term object.

name

The name of the contrast.

weights

A numeric matrix with one row per column of the term (row names are the term-level condition names from conditions(term, expand_basis = TRUE), in design-matrix column order) and one column per contrast (usually one).

condnames

Character vector of all expanded condition names from term.

contrast_spec

The original column_contrast_spec object.

A list containing the term, name, weights, condition names, and contrast specification.

A list containing the term, name, weights, condition names, and contrast specification.

A named list where each element is the result of calling contrast_weights on the corresponding contrast_spec in the set. The list names are the names of the individual contrasts.

A named list of contrast weight objects or matrices.

Details

If the weight matrices returned by a contrast specification contain row names, these are matched to the column names of the corresponding term in the design matrix. This allows contrasts to target only a subset of term levels.

Examples

des <- data.frame(
  onset = c(0, 10, 20, 30),
  run = 1,
  cond = factor(c("A", "B", "A", "B"))
)
sframe <- fmrihrf::sampling_frame(blocklens = 40, TR = 1)
cset <- contrast_set(
  diff = column_contrast(pattern_A = "cond.A", pattern_B = "cond.B", name = "diff")
)
emod <- event_model(onset ~ hrf(cond, contrasts = cset),
                    data = des, block = ~run, sampling_frame = sframe)
contrast_weights(emod)
#> $`cond#diff`
#> contrast: diff 
#>  A:  NULL 
#>  term:  cond 
#>  weights:  
#>        diff
#> cond.A    1
#> cond.B   -1
#>  conditions:  cond_cond.A cond_cond.B