Add function for creating subgraphs.

DESCRIPTION

 Package: rsAnalysis
 Title: High-Level Tools for rsfMRI analysis
-Version: 0.4.1
+Version: 0.4.2
 Authors@R: 
     person(given = "Christian",
            family = "Hohenfeld",

NAMESPACE

@@ -25,6 +25,7 @@ export(remove_loops)
 export(rs_pipeline)
 export(single_component_threshold)
 export(split_graph_list)
+export(to_subgraph)
 importFrom(magrittr,"%>%")
 importFrom(rlang,":=")
 importFrom(rlang,.data)

R/to_subgraph.R

+#' Take a list of graphs and return subgraphs.
+#'
+#' `to_subgraph` makes the assumption that all graphs share a common set of
+#' nodes like it is common with graph analysis of the brain.
+#'
+#' @param graph_list A list of tbl_graphs
+#' @param to_keep The names of the nodes to keep.
+#'
+#' @return A list of the graphs in `graph_list` reduced to the respective
+#' subgraphs.
+#' @export
+to_subgraph <- function(graph_list, to_keep) {
+    all_nodes <- graph_list[[1]] %>%
+        tidygraph::activate("nodes") %>%
+        tibble::as_tibble() %>%
+        tibble::deframe()
+
+    to_remove_net <- all_nodes[!all_nodes %in% to_keep]
+    graph_list <- lapply(graph_list,
+                         function(x) igraph::delete.vertices(x, to_remove_net))
+    graph_list <- lapply(graph_list, tidygraph::as_tbl_graph)
+    graph_list
+}

man/to_subgraph.Rd

+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/to_subgraph.R
+\name{to_subgraph}
+\alias{to_subgraph}
+\title{Take a list of graphs and return subgraphs.}
+\usage{
+to_subgraph(graph_list, to_keep)
+}
+\arguments{
+\item{graph_list}{A list of tbl_graphs}
+
+\item{to_keep}{The names of the nodes to keep.}
+}
+\value{
+A list of the graphs in `graph_list` reduced to the respective
+subgraphs.
+}
+\description{
+`to_subgraph` makes the assumption that all graphs share a common set of
+nodes like it is common with graph analysis of the brain.
+}

tests/testthat/test-to_subgraph.R

+describe("to_subgraph", {
+    data("graph_list")
+    it("creates a graph only containing the specified nodes", {
+        to_keep <- c("Precentral_L", "Precentral_R")
+        sub_list <- to_subgraph(graph_list, to_keep)
+        sub_order <- sapply(sub_list, igraph::gorder, USE.NAMES = FALSE)
+        expect_true(all(sub_order == length(to_keep)))
+    })
+})