Attaching ‘network’ first, ‘igraph’ second

One of the conflicting functions is add.edges(). When we call it from the console R starts looking for it in several places in a particular order. This can be inspected with search() function:

search()
## [1] ".GlobalEnv" "package:igraph" "package:network"
## [4] "package:pnmath" "package:stats" "package:graphics"
## [7] "package:grDevices" "package:utils" "package:datasets"
## [10] "package:methods" "Autoloads" "package:base"

So R will look in global environment (aka Workspace) first and then in the code provided by the attached packages as shown. Consequently:

# igraph version is on top
args(add.edges)
## function (graph, edges, ..., attr = list())
## NULL
# calling for version from network specifically
args(network::add.edges)
## function (x, tail, head, names.eval = NULL, vals.eval = NULL,
## ...)
## NULL

Because ‘network’ does not have a namespace some of its functions are masked by the copies from ‘igraph’. A call to some function from ‘network’ that uses one of those conflicting functions will use the version from the ‘igraph’ package (so trigger an error most likely) and not the correct version from ‘network’. For example:

x <- as.network(matrix(sample(0:1, 9, replace=TRUE), 3, 3))
## Error in set.vertex.attribute(g, "na", rep(FALSE, n), 1:n) :
##  Not a graph object

This tries to use set.vertex.attribute() from ‘igraph’ and not the correct one from ‘network’ because ‘igraph’ comes first on the search path as returned by search().

Attaching ‘igraph’ first, ‘network’ second

First some clean-up then loading the packages

detach(package:network, unload=TRUE)
detach(package:igraph, unload=TRUE)

# igraph first
library(igraph)
library(network)

Now the network version of add.edges() is on top

args(add.edges)
## function (x, tail, head, names.eval = NULL, vals.eval = NULL,
##  ...)
## NULL

Version from ‘igraph’ can be called with ::

args(igraph::add.edges)
## function (graph, edges, ..., attr = list())
## NULL

Given that we attached ‘igraph’ first and ‘network’ second based on the previous section we could expect that this will brake the functioning of the ‘igraph’ package. Let’s see this with V() function in ‘igraph’ which calls set.vertex.attribute() (a name conflict with ‘network’).

get("V<-")
## function (x, value)
## {
##  if (!is.igraph(x)) {
##  stop("Not a graph object")
##  }
##  if (!"name" %in% names(attributes(value)) || !"value" %in%
##  names(attributes(value))) {
##  stop("invalid indexing")
##  }
##  set.vertex.attribute(x, attr(value, "name"), index = value,
##  value = attr(value, "value"))
## }
## <environment: namespace:igraph>

Let’s check that:

g <- graph.full(3)
V(g)$type <- 1:3

And this works OK because for packages with namespaces R uses a little different searching mechanism. It searches in package namespace first, then among the functions imported by that package, then R base, and lastly in the “normal” search path (as from ‘search()’). See “Writing R Extensions”, last paragraph before the end of sub-section. Consequently, the correct version of ‘set.vertex.attribute’ is used.

Both packages have namespaces

If both packages have namespaces the errors like the one with ‘as.network’ shown above cannot happen. The code provided in the packages will work correctly as they will use their own copies of conflicting functions. Using the namespaced ‘network’ I made while creating ‘intergraph’:

library(network, lib="~/lib/R/2.11-dev")
## Loading ‘network’ from /home/mbojan/lib/R/2.11-dev/network
## Classes for Relational Data
## Version 1.4-1-1 created on 2008-11-17.
## copyright (c) 2005, Carter T. Butts, University of California-Irvine
##  Mark S. Handcock, University of Washington
##  David R. Hunter, Penn State University
##  Martina Morris, University of Washington
## For citation information, type citation("network").
## Type help("network-package") to get started.
## Modified by MB
## Loaded from “/home/mbojan/lib/R/2.11-dev”
library(igraph)
## Attaching package: 'igraph'

## The following object(s) are masked from 'package:network':

##  add.edges, add.vertices, %c%, delete.edges, delete.vertices,
##  get.edge.attribute, get.edges, get.vertex.attribute, is.bipartite,
##  is.directed, list.edge.attributes, list.vertex.attributes,
##  set.edge.attribute, set.vertex.attribute

net <- as.network(matrix(sample(0:1, 9, replace=TRUE), 3, 3))
net
## Network attributes:
## vertices = 3
## directed = TRUE
## hyper = FALSE
## loops = FALSE
## multiple = FALSE
## bipartite = FALSE
## total edges= 2
## missing edges= 0
## non-missing edges= 2
##
## Vertex attribute names:
## vertex.names
##
## adjacency matrix:
##   1 2 3
## 1 0 1 0
## 2 0 0 0
## 3 1 0 0

So, works OK even though we attached ‘network’ first and ‘igraph’ second.

Bottomline

1. Name conflicts between R packages will be inevitable given the pace at which number of package on CRAN grow.
2. Given that, using namespaces in packages is nowadays a necessity. See here how to do that.
3. If one of the conflicting packages does not have a namespace it seems OK if you attach the namespaced package first and the non-namespaced one later.
4. In case of name conflicts it is still the safest to use the :: operator and always specify what version (i.e. from which package) we want to use.