From d0353c9b01da1613bd70cb82661434b4278b9d8b Mon Sep 17 00:00:00 2001
From: Ben Raymond <ben.raymond@aad.gov.au>
Date: Wed, 11 Oct 2023 15:10:28 +1100
Subject: [PATCH] add latmin, latlax parms to land masking

---
 R/landmask.R     | 11 ++++-------
 man/gshhsMask.Rd |  4 ++--
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/R/landmask.R b/R/landmask.R
index 17f6c5c..dafe03c 100644
--- a/R/landmask.R
+++ b/R/landmask.R
@@ -13,21 +13,18 @@
 #' mask(0, c(100, -65)) ## test point lon,lat
 #'
 #' @export
-gshhsMask <- function(res = 0.1) {
-    if (!res %in% c(0.1, 0.05)) {
-        res <- 0.1
-    }
+gshhsMask <- function(res = 0.1, latmin = -90, latmax = 90) {
+    if (!res %in% c(0.1, 0.05)) res <- 0.1
     land.mask <- readPNG(system.file("extdata", paste0("land_mask_gshhs-", res, ".png"), package = "availability")) ## 0 = land, 1 = ocean
     if (length(dim(land.mask)) > 1) land.mask <- land.mask[, , 1]
     land.lon <- seq(from = -180+res/2, to = 180-res/2, length.out = dim(land.mask)[2])
     land.lat <- seq(from = 90-res/2, to = -90+res/2, length.out = dim(land.mask)[1])
     function(tm, pt) {
-        lonidx <- which.min(abs(land.lon-((pt[[1]]+180)%%360-180)))
-        latidx <- which.min(abs(land.lat-pt[[2]]))
-        land.mask[latidx, lonidx] > 0
+        (pt[[2]] > latmin) & (pt[[2]] < latmax) & (land.mask[which.min(abs(land.lat-pt[[2]])), which.min(abs(land.lon-((pt[[1]]+180)%%360-180)))] > 0)
     }
 }
 
+
 ##' @rdname gshhsMask
 ##' @export
 landmask_init <- gshhsMask
diff --git a/man/gshhsMask.Rd b/man/gshhsMask.Rd
index 074b97a..65f7959 100644
--- a/man/gshhsMask.Rd
+++ b/man/gshhsMask.Rd
@@ -5,9 +5,9 @@
 \alias{landmask_init}
 \title{A land mask based on the GSHHS data set}
 \usage{
-gshhsMask(res = 0.1)
+gshhsMask(res = 0.1, latmin = -90, latmax = 90)
 
-landmask_init(res = 0.1)
+landmask_init(res = 0.1, latmin = -90, latmax = 90)
 }
 \arguments{
 \item{res}{numeric: the spatial resolution of the mask, in degrees (either 0.1 or 0.05)}