closes #37

NAMESPACE

@@ -42,6 +42,7 @@ export(st_geod_distance)
 export(st_geod_length)
 export(st_geod_segmentize)
 export(st_geohash)
+export(st_geom_from_geohash)
 export(st_is_polygon_cw)
 export(st_linesubstring)
 export(st_minimum_bounding_circle)

NEWS.md

@@ -1,3 +1,7 @@
+# version 0.2-16
+
+* add `st_geom_from_geohash()`; #37
+
 # version 0.2-15
 
 * fix default for argument `digits` in `st_astext()`

R/RcppExports.R

@@ -57,6 +57,10 @@ CPL_geohash <- function(sfc, prec) {
     .Call('_lwgeom_CPL_geohash', PACKAGE = 'lwgeom', sfc, prec)
 }
 
+CPL_bbox_from_geohash <- function(h, prec) {
+    .Call('_lwgeom_CPL_bbox_from_geohash', PACKAGE = 'lwgeom', h, prec)
+}
+
 CPL_lwgeom_transform <- function(sfc, p4s) {
     .Call('_lwgeom_CPL_lwgeom_transform', PACKAGE = 'lwgeom', sfc, p4s)
 }

R/geohash.R

@@ -12,3 +12,22 @@
 st_geohash = function(x, precision = 0) {
 	CPL_geohash(st_geometry(x), precision)
 }
+
+#' @export
+#' @name st_geohash
+#' @param hash character vector with geohashes
+#' @param crs object of class `crs`
+#' @examples
+#' o = options(digits = 20)
+#' st_geom_from_geohash(c('9qqj7nmxncgyy4d0dbxqz0', 'u1hzz631zyd63zwsd7zt'))
+#' st_geom_from_geohash('9qqj7nmxncgyy4d0dbxqz0', 4) 
+#' st_geom_from_geohash('9qqj7nmxncgyy4d0dbxqz0', 10)
+#' options(o)
+st_geom_from_geohash = function(hash, precision = -1, crs = st_crs('OGC:CRS84')) {
+	stopifnot(is.character(hash), is.numeric(precision), length(precision) == 1)
+	m = CPL_bbox_from_geohash(hash, as.integer(precision))
+	bb = matrix(m, nrow = 4)
+	rownames(bb) = c("xmin", "ymin", "xmax", "ymax")
+	bb = apply(bb, 2, sf::st_bbox, simplify = FALSE)
+	sf::st_set_crs(do.call(c, lapply(bb, sf::st_as_sfc)), crs)
+}

configure

@@ -3978,7 +3978,7 @@ OBJECTS="${OBJECTS} \$(OBJECTS_LIBLWGEOM)"
 
 
 # Must keep the leading ${CPPFLAGS} or the previous CPPFLAGS don't get saved
-PKG_CPPFLAGS="${CPPFLAGS} ${PKG_CPPFLAGS} -I./liblwgeom -DHAVE_LIBGEOM_INTERNAL_H"
+PKG_CPPFLAGS="${CPPFLAGS} ${PKG_CPPFLAGS} -I./liblwgeom -DHAVE_LIBLWGEOM_INTERNAL_H"
 
 
 #

configure.ac

@@ -509,7 +509,7 @@ AC_CHECK_LIB(geos_c, GEOS_init_r,
 AC_SUBST([OBJECTS], ["${OBJECTS} \$(OBJECTS_LIBLWGEOM)"])
 
 # Must keep the leading ${CPPFLAGS} or the previous CPPFLAGS don't get saved
-AC_SUBST([PKG_CPPFLAGS], ["${CPPFLAGS} ${PKG_CPPFLAGS} -I./liblwgeom -DHAVE_LIBGEOM_INTERNAL_H"])
+AC_SUBST([PKG_CPPFLAGS], ["${CPPFLAGS} ${PKG_CPPFLAGS} -I./liblwgeom -DHAVE_LIBLWGEOM_INTERNAL_H"])
 
 #
 # concluding substitution

src/RcppExports.cpp

@@ -182,6 +182,18 @@ BEGIN_RCPP
     return rcpp_result_gen;
 END_RCPP
 }
+// CPL_bbox_from_geohash
+Rcpp::NumericVector CPL_bbox_from_geohash(Rcpp::CharacterVector h, int prec);
+RcppExport SEXP _lwgeom_CPL_bbox_from_geohash(SEXP hSEXP, SEXP precSEXP) {
+BEGIN_RCPP
+    Rcpp::RObject rcpp_result_gen;
+    Rcpp::RNGScope rcpp_rngScope_gen;
+    Rcpp::traits::input_parameter< Rcpp::CharacterVector >::type h(hSEXP);
+    Rcpp::traits::input_parameter< int >::type prec(precSEXP);
+    rcpp_result_gen = Rcpp::wrap(CPL_bbox_from_geohash(h, prec));
+    return rcpp_result_gen;
+END_RCPP
+}
 // CPL_lwgeom_transform
 Rcpp::List CPL_lwgeom_transform(Rcpp::List sfc, Rcpp::CharacterVector p4s);
 RcppExport SEXP _lwgeom_CPL_lwgeom_transform(SEXP sfcSEXP, SEXP p4sSEXP) {
@@ -361,6 +373,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"_lwgeom_CPL_split", (DL_FUNC) &_lwgeom_CPL_split, 2},
     {"_lwgeom_CPL_wrap_x", (DL_FUNC) &_lwgeom_CPL_wrap_x, 3},
     {"_lwgeom_CPL_geohash", (DL_FUNC) &_lwgeom_CPL_geohash, 2},
+    {"_lwgeom_CPL_bbox_from_geohash", (DL_FUNC) &_lwgeom_CPL_bbox_from_geohash, 2},
     {"_lwgeom_CPL_lwgeom_transform", (DL_FUNC) &_lwgeom_CPL_lwgeom_transform, 2},
     {"_lwgeom_CPL_minimum_bounding_circle", (DL_FUNC) &_lwgeom_CPL_minimum_bounding_circle, 1},
     {"_lwgeom_CPL_subdivide", (DL_FUNC) &_lwgeom_CPL_subdivide, 2},

src/lwgeom.cpp

@@ -137,6 +137,24 @@ Rcpp::CharacterVector CPL_geohash(Rcpp::List sfc, int prec) {
 	return chr;
 }
 
+// [[Rcpp::export]]
+Rcpp::NumericVector CPL_bbox_from_geohash(Rcpp::CharacterVector h, int prec) {
+
+	// void decode_geohash_bbox(char *geohash, double *lat, double *lon, int precision)
+	Rcpp::NumericVector ret(4 * h.size()); // return
+	double lat[2], lon[2];
+	char *hash;
+	for (size_t i = 0; i < h.size(); i++) {
+		hash = h[i];
+		decode_geohash_bbox(hash, lat, lon, prec);
+		ret[4 * i + 0] = lon[0];
+		ret[4 * i + 1] = lat[0];
+		ret[4 * i + 2] = lon[1];
+		ret[4 * i + 3] = lat[1];
+	}
+	return ret;
+}
+
 // [[Rcpp::export]]
 Rcpp::List CPL_lwgeom_transform(Rcpp::List sfc, Rcpp::CharacterVector p4s) {
 	if (p4s.size() != 2)