Subset MID Objects

S3 methods to extract parts of a "midlist" or "midrib" collection object.

Usage

# S3 method for class 'midlist'
x[i, drop = if (missing(i)) TRUE else length(i) == 1L]

# S3 method for class 'midrib'
x[i, drop = if (missing(i)) TRUE else length(i) == 1L]

# S3 method for class 'midrib'
x[[i, exact = TRUE]]

Arguments

x

a collection object of class "midlist" or "midrib".

i

indices specifying elements to extract. Can be numeric, character, or logical vectors.

drop

logical. If TRUE the result is coerced to the lowest possible dimension. For a collection (e.g., "mids"), extracting a single element drops it to a base object (e.g., "mid").

exact

logical. If TRUE, exact matching is used for character strings.

Value

[ returns a subsetted collection object or a single base object if drop = TRUE.

[[ returns a single base object.

Details

A "midlist" or "midrib" object stores multiple objects of the same single base class: "mid", "midimp", "midcon", or "midbrk".

When extracting items using [, it returns a subsetted "midlist" or "midrib" object, preserving its collection class (e.g., "mids", "midimps"). By default, if a single base object is extracted (length(i) == 1L) and drop = TRUE, the object is simplified to a single base object (e.g., "mid", "midimp"). [[ always extracts a single base object.

See also

midlist, labels.midlist

Examples

# Fit a multivariate linear model
fit <- lm(cbind(y1, y2, y3) ~ x1 + I(x1^2), data = anscombe)

# Interpret the linear models
collection <- interpret(cbind(y1, y2, y3) ~ x1, data = anscombe, model = fit)

# Check the default labels
labels(collection)
#> [1] "y1" "y2" "y3"

# Rename the models in the collection
labels(collection) <- letters[1L:3L]
labels(collection)
#> [1] "a" "b" "c"

# Extract a single base "mid" object by its new name using [[
mid <- collection[["a"]]
class(mid)
#> [1] "mid"

# Subset the collection to keep only the first two models using [
sub <- collection[1:2]
class(sub) # Maintains the collection class (e.g., "mids"-"midrib")
#> [1] "mids"   "midrib"