write listw to ArcGIS SWM dbf format

NAMESPACE

@@ -42,7 +42,7 @@ export(gabrielneigh, geary.test, geary, geary.mc, globalG.test, graph2nb,
 	knearneigh, knn2nb)
 
 export(listw2sn, sn2listw, read.gwt2nb,	write.sn2gwt,
-        read.swmdbf2listw, read_swm_dbf, write.sn2DBF,
+        read.swmdbf2listw, read_swm_dbf, write.swmdbf, write_swm_dbf, write.sn2DBF,
         lm.LMtests, lm.RStests, SD.RStests,
 	lm.morantest, localG, localG_perm, localmoran, localmoran_perm, moran,
 	moran.test, moran.mc, moran.plot, localmoran.sad, lm.morantest.sad,

R/read.gwt2nb.R

@@ -207,6 +207,7 @@ read.swmdbf2listw <- function(fn, region.id=NULL, style=NULL, zero.policy=NULL)
     if (is.null(style)) {
         style <- "M"
     }
+
     if (style == "M")
         warning("style is M (missing); style should be set to a valid value")
 
@@ -215,6 +216,19 @@ read.swmdbf2listw <- function(fn, region.id=NULL, style=NULL, zero.policy=NULL)
     if (requireNamespace("foreign", quietly=TRUE)) {
         df <- try(foreign::read.dbf(fn, as.is=TRUE), silent=TRUE)
         if (inherits(df, "try-error")) stop(df[1])
+				# a SWM table that is _imported_ into ArcGIS Pro does not use the
+			  # leading empty `Field1`. If it is not present, add it for this
+			  # function to continue as anticipated
+				dbf_names <- colnames(df)
+				nb_idx <- which(dbf_names == "NID")
+				# ensure that `NID` is provided
+				if (length(nb_idx) == 0) stop("Field `NID` not found in provided .dbf")
+				if (nb_idx == 2L) {
+					df <- cbind(
+						Field1 = rep(0, nrow(df)),
+						df
+					)
+				}
         if (is.null(region.id)) {
             rn <- range(c(df[,2], df[,3]))
             region.id <- as.character(rn[1]:rn[2])
@@ -246,3 +260,40 @@ read.swmdbf2listw <- function(fn, region.id=NULL, style=NULL, zero.policy=NULL)
 read_swm_dbf <- function(fn) {
     read.swmdbf2listw(fn, style="B")
 }
+
+write.swmdbf <- function(listw, file, ind, region.id = attr(listw, "region.id")) {
+  stopifnot(
+    "`ind` must be a character scalar" = is.character(ind),
+    "`ind` must be a character scalar" = length(ind) == 1,
+    "`listw` must be a `listw` spatial weights matrix" = inherits(listw, "listw"),
+		"package foreign is required to write to dbf" = requireNamespace("foreign")
+  )
+
+  n <- length(listw$neighbours)
+
+  # Unsure if it is possible to not have region.id in current state 
+  # of spdep, including in the event.
+  if (is.null(region.id)) {
+    warning("`region.id` not supplied. Using row positions.")
+    region.id <- as.character(1:n)
+  }
+
+  # create indices from indices to match length of neighbors
+  from <- region.id[rep.int(1:n, card(listw$neighbours))]
+  # flatten the neighbor ids
+  to <- region.id[unlist(listw$neighbours)]
+  # flatten the weights
+  weight <- unlist(listw$weights)
+  # construct a data frame from the flattened structure
+  res <- data.frame(from, to, weight)
+
+  # give appropriate column names. The first column must be 
+  # the unique ID column
+  colnames(res) <- c(ind, "NID", "WEIGHT")
+  foreign::write.dbf(res, file)
+  invisible(res)
+}
+
+write_swm_dbf <- function(listw, file, ind, region.id = attr(listw, "region.id")) {
+	write.swmdbf(listw, file, ind, region.id)
+}

man/read.gwt2nb.Rd

@@ -5,6 +5,8 @@
 \alias{read.dat2listw}
 \alias{read.swmdbf2listw}
 \alias{read_swm_dbf}
+\alias{write.swmdbf}
+\alias{write_swm_dbf}
 \alias{write.sn2dat}
 \alias{write.sn2DBF}
 %- Also NEED an '\alias' for EACH other topic documented here.
@@ -19,12 +21,15 @@ read.dat2listw(file)
 write.sn2dat(sn, file)
 read.swmdbf2listw(fn, region.id=NULL, style=NULL, zero.policy=NULL)
 read_swm_dbf(fn)
+write.swmdbf(listw, file, ind, region.id = attr(listw, "region.id"))
+write_swm_dbf(listw, file, ind, region.id = attr(listw, "region.id"))
 write.sn2DBF(sn, file)
 }
 %- maybe also 'usage' for other objects documented here.
 \arguments{
   \item{file, fn}{name of file with weights data}
   \item{region.id}{a character vector of region IDs - for ArcGIS SWM DBFs, the values must be character integers (only numbers not starting with zero)}
+  \item{listw}{a \code{listw} object}
   \item{sn}{a \code{spatial.neighbour} object}
   \item{shpfile}{character string: if not given Shapefile name taken from GWT file for this dataset}
   \item{ind}{character string: region id indicator field name}