From ac72c2472f25a927b89c1ef42daf826c4091ab32 Mon Sep 17 00:00:00 2001
From: jhardenberg <hardenberg@gmail.com>
Date: Sat, 23 Nov 2019 01:30:33 +0100
Subject: [PATCH 1/2] make lon monotonic always

---
 R/CST_RFWeights.R | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/R/CST_RFWeights.R b/R/CST_RFWeights.R
index d6cae379..b552a8e1 100644
--- a/R/CST_RFWeights.R
+++ b/R/CST_RFWeights.R
@@ -54,31 +54,37 @@ CST_RFWeights <- function(climfile, nf, lon, lat, varname = "", fsmooth=TRUE) {
     warning(paste0("lon: [", lon[1], ", ", lon[length(lon)], "] ",
                  " lat: [", lat[1], ", ", lat[length(lat)], "]"))
   }
-  
-  ncin <- nc_open(climfile) 
-  latin <- ncvar_get(ncin, grep("lat", attributes(ncin$dim)$names, value = TRUE))
-  lonin <- ncvar_get(ncin, grep("lon", attributes(ncin$dim)$names, value = TRUE))
-  if ( varname == "") {
+
+  ncin <- nc_open(climfile)
+  latin <- ncvar_get(ncin, grep("lat", attributes(ncin$dim)$names,
+                                value = TRUE))
+  lonin <- ncvar_get(ncin, grep("lon", attributes(ncin$dim)$names,
+                                value = TRUE))
+  if (varname == "") {
     varname <- grep("bnds", attributes(ncin$var)$names,
                     invert = TRUE, value = TRUE)[1]
   }
   zclim <- ncvar_get(ncin, varname)
 
-# Check if lon and lat need to be reversed
-  if ( lat[1] > lat[2] ) {
-    lat <- rev(lat) 
-    frev = TRUE
+  # Check if lon and lat need to be reversed
+  if (lat[1] > lat[2]) {
+    lat <- rev(lat)
+    frev <- TRUE
   } else {
-    frev = FALSE
+    frev <- FALSE
   }
-  if ( latin[1] > latin[2] ) {
+  if (latin[1] > latin[2]) {
     latin <- rev(latin)
-    zclim = zclim[,seq(dim(zclim)[2],1)]
+    zclim <- zclim[, seq(dim(zclim)[2], 1)]
+  }
+  # If lon is not monotonic make it so
+  if (lon[1] > tail(lon, 1)) {
+    lon <- (lon - 360) * (lon > tail(lon, 1)) + lon * (lon <= tail(lon, 1))
   }
   ww <- rfweights(zclim, lonin, latin, lon, lat, nf, fsmooth = fsmooth)
-  if ( frev ) {
-    ww = ww[,seq(dim(ww)[2],1)]
+  if (frev) {
+    ww <- ww[, seq(dim(ww)[2], 1)]
   }
-  attributes(dim(ww))$names <- c("lon","lat")
+  attributes(dim(ww))$names <- c("lon", "lat")
   return(ww)
 }
-- 
GitLab


From 93bfe8c488eb87929d88e19ffd030ea2719211c5 Mon Sep 17 00:00:00 2001
From: jhardenberg <hardenberg@gmail.com>
Date: Sat, 23 Nov 2019 18:08:48 +0100
Subject: [PATCH 2/2] shift global climatology as needed

---
 R/CST_RFWeights.R | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/R/CST_RFWeights.R b/R/CST_RFWeights.R
index b552a8e1..ec44d13c 100644
--- a/R/CST_RFWeights.R
+++ b/R/CST_RFWeights.R
@@ -81,6 +81,32 @@ CST_RFWeights <- function(climfile, nf, lon, lat, varname = "", fsmooth=TRUE) {
   if (lon[1] > tail(lon, 1)) {
     lon <- (lon - 360) * (lon > tail(lon, 1)) + lon * (lon <= tail(lon, 1))
   }
+  # Is the reference climatology global in the zonal direction ?
+  # Test if the the first and the last longitude are close
+  dx <- abs((tail(lonin, 1) %% 360) - (lonin[1] %% 360))
+  # Shortest distance on a torus
+  if (dx > 180) {
+        dx <- 360 - dx
+  }
+  # If this distance is smaller than twice the grid spacing we are global
+  if (dx <= (lonin[2] - lonin[1]) * 2) {
+    # Is the target area not fully inside the reference climatology area ?
+    if (lon[1] < lonin[1]) {
+      # Shift lonin to the west by 180 degrees
+      nn <- length(lonin)
+      zclim0 <- zclim
+      zclim[1:(nn / 2), ] <- zclim0[(nn / 2 + 1):nn, ]
+      zclim[(nn / 2 + 1):nn, ] <- zclim0[1:(nn / 2), ]
+      lonin <- lonin - 180
+    } else if (tail(lon, 1) > tail(lonin, 1)) {
+      # Shift lonin to the east by 180 degrees
+      nn <- length(lonin)
+      zclim0 <- zclim
+      zclim[1:(nn / 2), ] <- zclim0[(nn / 2 + 1):nn, ]
+      zclim[(nn / 2 + 1):nn, ] <- zclim0[1:(nn / 2), ]
+      lonin <- lonin + 180
+    }
+  }
   ww <- rfweights(zclim, lonin, latin, lon, lat, nf, fsmooth = fsmooth)
   if (frev) {
     ww <- ww[, seq(dim(ww)[2], 1)]
-- 
GitLab