[R] Error in if (class(networks) == "matrix") from a function

[Chao Liu]

Thank you Eric, Andrew, Rui and Martin for all your help and advice. I did
learn some good practices under the new R version!

Best,

Chao

On Thu, Sep 22, 2022 at 5:53 AM Martin Maechler <maechler using stat.math.ethz.ch>
wrote:

> >>>>> Eric Berger
> >>>>>     on Wed, 21 Sep 2022 22:26:39 +0300 writes:
>
>     > In R 4.2.0 there is a significant change. When you use an if()
> statement
>     > with a condition of length > 1 this now reports an error.
>     > e.g. this link mentions it as a change
>     > https://www.jumpingrivers.com/blog/new-features-r420/
>
>     > In your case this is because class(obj) can return a character
> vector of
>     > length > 1 (all the classes).
>     > One possible workaround would be:
>
>     > if ( "matrix" %in% class(networks) ) ...
>
> Yes,  however, in general, the recommendation in the related R
> blog,
>
> would have been
>
>       if(inherits(networks, "matrix"))
>
> which I consider better *correctly readable* (and also expect
> to be more efficient).
>
> Lastly, in this special case, I'd try
>
>         if(is.matrix(networks))
>
> i.e., I'd try to see if the fast  is.matrix(.)  applies to your 'networks'
> (and I'm guessing "yes" with high confidence ..).
>
> Martin
>
>     > HTH,
>     > Eric
>
>
>     > On Wed, Sep 21, 2022 at 10:21 PM Chao Liu <psychaoliu using gmail.com>
> wrote:
>
>     >> Dear R-Help community,
>     >>
>     >> This is a crosspost on SO but I've had no luck so far. So I have a
> function
>     >> which computes a centrality index for the nodes in a network or
> matrix.
>     >> Here is the function:
>     >>
>     >> library(igraph) #load package igraph
>     >> centrality <- function (networks, type = c("indegree", "outdegree",
>     >> "freeman",
>     >> "betweenness", "flow", "closeness", "eigenvector", "information",
>     >> "load", "bonpow"), directed = TRUE, lag = 0, rescale = FALSE,
>     >> center = FALSE, coefname = NULL, ...) {
>     >> if (is.null(directed) || !is.logical(directed)) {
>     >> stop("'directed' must be TRUE or FALSE.")
>     >> }
>     >> else if (length(directed) != 1) {
>     >> stop("The 'directed' argument must contain a single logical
>     >> value only.")
>     >> }
>     >> else if (directed == FALSE) {
>     >> gmode <- "graph"
>     >> }
>     >> else {
>     >> gmode <- "digraph"
>     >> }
>     >> objects <- checkDataTypes(y = NULL, networks = networks,
>     >> lag = lag)
>     >> centlist <- list()
>     >> for (i in 1:objects$time.steps) {
>     >> if (type[1] == "indegree") {
>     >> cent <- degree(objects$networks[[i]], gmode = gmode,
>     >> cmode = "indegree", rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "outdegree") {
>     >> cent <- degree(objects$networks[[i]], gmode = gmode,
>     >> cmode = "outdegree", rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "freeman") {
>     >> cent <- degree(objects$networks[[i]], gmode = gmode,
>     >> cmode = "freeman", rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "betweenness") {
>     >> cent <- betweenness(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "flow") {
>     >> cent <- flowbet(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "closeness") {
>     >> cent <- closeness(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "eigenvector") {
>     >> cent <- evcent(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "information") {
>     >> cent <- infocent(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "load") {
>     >> cent <- loadcent(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, ...)
>     >> }
>     >> else if (type[1] == "bonpow") {
>     >> cent <- bonpow(objects$networks[[i]], gmode = gmode,
>     >> rescale = rescale, tol = 1e-20, ...)
>     >> }
>     >> else {
>     >> stop("'type' argument was not recognized.")
>     >> }
>     >> centlist[[i]] <- cent
>     >> }
>     >> time <- numeric()
>     >> y <- numeric()
>     >> for (i in 1:objects$time.steps) {
>     >> time <- c(time, rep(i, objects$n[[i]]))
>     >> if (is.null(centlist[[i]])) {
>     >> y <- c(y, rep(NA, objects$n[[i]]))
>     >> }
>     >> else {
>     >> if (center == TRUE) {
>     >> centlist[[i]] <- centlist[[i]] - mean(centlist[[i]],
>     >> na.rm = TRUE)
>     >> }
>     >> y <- c(y, centlist[[i]])
>     >> }
>     >> }
>     >> if (is.null(coefname) || !is.character(coefname) ||
> length(coefname) >
>     >> 1) {
>     >> coeflabel <- ""
>     >> }
>     >> else {
>     >> coeflabel <- paste0(".", coefname)
>     >> }
>     >> if (lag == 0) {
>     >> laglabel <- ""
>     >> }
>     >> else {
>     >> laglabel <- paste0(".lag", paste(lag, collapse = "."))
>     >> }
>     >> label <- paste0(type[1], coeflabel, laglabel)
>     >> dat <- data.frame(y, time = time, node = objects$nodelabels)
>     >> dat$node <- as.character(dat$node)
>     >> colnames(dat)[1] <- label
>     >> attributes(dat)$lag <- lag
>     >> return(dat)}
>     >>
>     >> Here is the matrix:
>     >>
>     >> dat <- read.table(text="A B #this is edgelist
>     >> 1 2
>     >> 1 3
>     >> 1 2
>     >> 2 1
>     >> 2 3
>     >> 3 1
>     >> 3 2
>     >> 3 1", header=TRUE)
>     >> datmat <- as.matrix(get.adjacency(graph.edgelist(as.matrix(dat),
>     >> directed=TRUE))) #this is the matrix
>     >> colnames(datmat) <- c("1", "2", "3") #rename the columns
>     >>
>     >> When I applied the function to a matrix
>     >> centrality(datmat,type="flow",center=TRUE), it returns the error:
>     >>
>     >> Error in if (class(networks) == "matrix") { :
>     >> the condition has length > 1
>     >>
>     >> What is the cause of this error? How to fix it? Any help will be
> greatly
>     >> appreciated!
>     >>
>     >>
>     >> Best,
>     >>
>     >> Chao
>     >>
>     >> [[alternative HTML version deleted]]
>     >>
>     >> ______________________________________________
>     >> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>     >> https://stat.ethz.ch/mailman/listinfo/r-help
>     >> PLEASE do read the posting guide
>     >> http://www.R-project.org/posting-guide.html
>     >> and provide commented, minimal, self-contained, reproducible code.
>     >>
>
>     > [[alternative HTML version deleted]]
>
>     > ______________________________________________
>     > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>     > https://stat.ethz.ch/mailman/listinfo/r-help
>     > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
>     > and provide commented, minimal, self-contained, reproducible code.
>

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