Given a distance matrix, return information above it, including dimension, sparsity information, unmatchable members, summary of finite distances, and, in the case of BlockedInfinitySparseMatrix, block structure.

## Usage

# S3 method for InfinitySparseMatrix
summary(object, ..., distanceSummary = TRUE)

# S3 method for BlockedInfinitySparseMatrix
summary(
object,
...,
distanceSummary = TRUE,
printAllBlocks = FALSE,
blockStructure = TRUE
)

# S3 method for DenseMatrix
summary(object, ..., distanceSummary = TRUE)

## Arguments

object

A InfinitySparseMatrix, BlockedInfinitySparseMatrix or DenseMatrix.

...

Ignored.

distanceSummary

Default TRUE. Should a summary of minimum distance per treatment member be calculated? May be slow on larger data sets.

printAllBlocks

If object is a BlockedInfinitySparseMatrix, should summaries of all blocks be printed alongside the overall summary? Default FALSE.

blockStructure

If object is a BlockedInfinitySparseMatrix and printAllBlocks is false, print a quick summary of each individual block. Default TRUE. If the number of blocks is high, consider suppressing this.

## Value

A named list. The summary for an

InfinitySparseMatrix or DenseMatrix contains the following:

• total: Contains the total number of treatment and control members, as well as eligible and ineligible matches.

• matchable: The names of all treatment and control members with at least one eligible match.

• unmatchable: The names of all treatment and control members with no eligible matches.

• distances: The summary of minimum matchable distances, if distanceSummary is TRUE.

For BlockedInfinitySparseMatrix, the named list

instead of contains one entry per block, named after each block (i.e. the value of the blocking variable) as well as a block named 'overall' which contains the summary ignoring blocks. Each of these entries contains a list with entries 'total', 'matchable', 'unmatchable' and 'distances', as described above.

## Details

The output consists of several pieces.

• Membership: Indicates the dimension of the distance.

• Total (in)eligible potential matches: A measure of the sparsity of the distance. Eligible matches have a finite distance between treatment and control members; they could be matched. Ineligible matches have Inf distance and can not be matched. A higher number of ineligible matches can speed up matching, but runs the risk of less optimal overall matching results.

• Unmatchable treatment/control members: If any observations have no eligible matches (e.g. their distance to every potential match is Inf) they are listed here. See Value below for details of how to access lists of matchable and unmatchable treatment and control members.

• Summary of minimum matchable distance per treatment member: To assist with choosing a caliper, this is a numeric summary of the smallest distance per matchable treatment member. If you provide a caliper that is less than the maximum value, at least one treatment member will become unmatchable.

• Block structure: For BlockedInfinitySparseMatrix, a quick summary of the structure of each individual block. (The above will all be across all blocks.) This may indicate which blocks, if any, are problematic.