# create_list_from_mat: Create a list representation of a distance matrix. In match2C: Match One Sample using Two Criteria

## Description

This function creates a “list representation” of a treatment-by-control distance matrix.

## Usage

 ```1 2 3 4 5 6 7 8``` ```create_list_from_mat( Z, dist_mat, p = NULL, caliper = NULL, k = NULL, penalty = Inf ) ```

## Arguments

 `Z` A length (n = n_t + n_c) vector of treatment indicators. `dist_mat` A treatment-by-control (n_t-by-n_c) distance matrix. `p` A vector of length (n_t + n_c) on which caliper applies (e.g. propensity scores) `caliper` Size of the caliper. `k` Connect each treated to the nearest k controls `penalty` Penalty for violating the caliper. Set to Inf by default.

## Details

This function creates a list representation of a treatment-by-control network. The list representation can be made sparse using a user-specified caliper. A list representation of a treatment-by-control distance matrix consists of the following arguments:

• start_n: a vector containing the node numbers of the start nodes of each arc in the network.

• end_n: a vector containing the node numbers of the end nodes of each arc in the network.

• d: a vector containing the integer cost of each arc in the network.

Node 1,2,...,n_t are n_t treatment nodes; n_t + 1, n_t + 2, ..., n_t + n_c are n_c control nodes. start_n, end_n, and d should have the same lengths, all of which equal to the number of edges.

There are two options for users to make a network sparse. Option caliper is a value applied to the vector p to avoid connecting treated to controls whose covariate or propensity score defined by p is outside p +/- caliper. Second, within a specified caliper, sometimes there are still too many controls connected to each treated, and we can further trim down this number up to k by restricting our attention to the k nearest (in p) to each treated.

By default a hard caliper is applied, i.e., option penalty is set to Inf by default. Users may make the caliper a soft one by setting penalty to a large yet finite number.

## Value

This function returns a list that consists of three arguments: start_n, end_n, and d, as described above.

match2C documentation built on May 9, 2021, 9:07 a.m.