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#' Is this object an igraph graph?
#'
#' @description
#' `r lifecycle::badge("deprecated")`
#'
#' `is.igraph()` was renamed to `is_igraph()` to create a more
#' consistent API.
#' @inheritParams is_igraph
#' @keywords internal
#' @export
is.igraph <- function(graph) { # nocov start
lifecycle::deprecate_soft("2.0.0", "is.igraph()", "is_igraph()")
is_igraph(graph = graph)
} # nocov end
# IGraph R package
# Copyright (C) 2005-2012 Gabor Csardi <csardi.gabor@gmail.com>
# 334 Harvard street, Cambridge, MA 02139 USA
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
#
###################################################################
#' Is this object an igraph graph?
#'
#' @param graph An R object.
#' @return A logical constant, `TRUE` if argument `graph` is a graph
#' object.
#' @author Gabor Csardi \email{csardi.gabor@@gmail.com}
#' @export
#' @keywords graphs
#' @examples
#'
#' g <- make_ring(10)
#' is_igraph(g)
#' is_igraph(numeric(10))
is_igraph <- function(graph) {
if (!inherits(graph, "igraph")) {
return(FALSE)
}
warn_version(graph)
TRUE
}
#' Incident vertices of some graph edges
#' @description
#' `r lifecycle::badge("deprecated")`
#'
#' Use [ends()].
#' @inheritParams ends
#' @export
#' @keywords internal
get.edge <- function(graph, id) {
lifecycle::deprecate_stop("2.1.0", "get.edge()", "ends()")
}
#' Head of the edge(s) in a graph
#'
#' For undirected graphs, head and tail is not defined. In this case
#' `head_of()` returns vertices incident to the supplied edges, and
#' `tail_of()` returns the other end(s) of the edge(s).
#'
#' @param graph The input graph.
#' @param es The edges to query.
#' @return A vertex sequence with the head(s) of the edge(s).
#'
#' @family structural queries
#'
#' @export
head_of <- function(graph, es) {
create_vs(graph, ends(graph, es, names = FALSE)[, 2])
}
#' Tails of the edge(s) in a graph
#'
#' For undirected graphs, head and tail is not defined. In this case
#' `tail_of()` returns vertices incident to the supplied edges, and
#' `head_of()` returns the other end(s) of the edge(s).
#'
#' @param graph The input graph.
#' @param es The edges to query.
#' @return A vertex sequence with the tail(s) of the edge(s).
#'
#' @family structural queries
#'
#' @export
tail_of <- function(graph, es) {
create_vs(graph, ends(graph, es, names = FALSE)[, 1])
}
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