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.

## 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.