我正在嘗試計算R中空間對象的氣候變量的平均值。挑戰在於,我試圖爲每個2級行政區域計算這些方法在世界上(www.gadm.org),我需要一種有效的統計計算方法。我已經計算出了這些統計數據,但是對於面積較小的區域定義沒有問題,這些定義跨越了較少的氣候區域/瓦片,但後勤問題已成爲將此任務擴展到全球的障礙。計算R中大量柵格和空間對象的地理空間統計信息
我已經嘗試過使用gadm.org的全球二級邊界shapefile,然後導入併合並worldclim.org的一組完整的bioclimatic柵格(以最高可用空間分辨率)和zone/tiles,但似乎對資源要求太高。具體來說,將整套柵格區域/拼貼合併爲一個全局柵格對象的操作永遠不會結束。這似乎是最有效的方法,也是最有可能最小化錯誤的方法,將整個世界的柵格區域合併在一起。
我不確定如何從這裏解決問題,因爲按國別計算這些統計數據似乎非常繁瑣和低效。此外,行政邊界圖層中有大量形狀與單個Worldclim區域/圖塊重疊,如果相關氣候物體從計算中不存在的相關氣候物體完全位於單個區域/圖塊中,則會導致錯誤。
我想知道如何才能拿出一個有效的解決方案,給出了操作的大小。
下載2級全球行政邊界數據後,我曾嘗試下面的代碼:
library(raster)
library(rgdal)
library(maptools)
library(foreign)
#SET WORKING DIRECTORY
setwd("C:/gadm28")
#IMPORT GLOBAL ADMINISTRATIVE BOUNDARIES (LEVEL 2) DATA FROM HARD DRIVE
gadm <- readOGR(dsn="C:/gadm28", layer="gadm28")
#IMPORT GLOBAL (ALL TILES) BIOCLIMACTIC DATA DIRECTLY FROM WORLDCLIM.ORG
climatezone00 <- getData('worldclim', var='bio', res=0.5, lon=-180, lat=90)
climatezone01 <- getData('worldclim', var='bio', res=0.5, lon=-150, lat=90)
climatezone02 <- getData('worldclim', var='bio', res=0.5, lon=-120, lat=90)
climatezone03 <- getData('worldclim', var='bio', res=0.5, lon=-90, lat=90)
climatezone04 <- getData('worldclim', var='bio', res=0.5, lon=-60, lat=90)
climatezone05 <- getData('worldclim', var='bio', res=0.5, lon=-30, lat=90)
climatezone06 <- getData('worldclim', var='bio', res=0.5, lon=0, lat=90)
climatezone07 <- getData('worldclim', var='bio', res=0.5, lon=30, lat=90)
climatezone08 <- getData('worldclim', var='bio', res=0.5, lon=60, lat=90)
climatezone09 <- getData('worldclim', var='bio', res=0.5, lon=90, lat=90)
climatezone010 <- getData('worldclim', var='bio', res=0.5, lon=120, lat=90)
climatezone011 <- getData('worldclim', var='bio', res=0.5, lon=150, lat=90)
climatezone10 <- getData('worldclim', var='bio', res=0.5, lon=-180, lat=60)
climatezone11 <- getData('worldclim', var='bio', res=0.5, lon=-150, lat=60)
climatezone12 <- getData('worldclim', var='bio', res=0.5, lon=-120, lat=60)
climatezone13 <- getData('worldclim', var='bio', res=0.5, lon=-90, lat=60)
climatezone14 <- getData('worldclim', var='bio', res=0.5, lon=-60, lat=60)
climatezone15 <- getData('worldclim', var='bio', res=0.5, lon=-30, lat=60)
climatezone16 <- getData('worldclim', var='bio', res=0.5, lon=0, lat=60)
climatezone17 <- getData('worldclim', var='bio', res=0.5, lon=30, lat=60)
climatezone18 <- getData('worldclim', var='bio', res=0.5, lon=60, lat=60)
climatezone19 <- getData('worldclim', var='bio', res=0.5, lon=90, lat=60)
climatezone110 <- getData('worldclim', var='bio', res=0.5, lon=120, lat=60)
climatezone111 <- getData('worldclim', var='bio', res=0.5, lon=150, lat=60)
climatezone20 <- getData('worldclim', var='bio', res=0.5, lon=-180, lat=30)
climatezone21 <- getData('worldclim', var='bio', res=0.5, lon=-150, lat=30)
climatezone22 <- getData('worldclim', var='bio', res=0.5, lon=-120, lat=30)
climatezone23 <- getData('worldclim', var='bio', res=0.5, lon=-90, lat=30)
climatezone24 <- getData('worldclim', var='bio', res=0.5, lon=-60, lat=30)
climatezone25 <- getData('worldclim', var='bio', res=0.5, lon=-30, lat=30)
climatezone26 <- getData('worldclim', var='bio', res=0.5, lon=0, lat=30)
climatezone27 <- getData('worldclim', var='bio', res=0.5, lon=30, lat=30)
climatezone28 <- getData('worldclim', var='bio', res=0.5, lon=60, lat=30)
climatezone29 <- getData('worldclim', var='bio', res=0.5, lon=90, lat=30)
climatezone210 <- getData('worldclim', var='bio', res=0.5, lon=120, lat=30)
climatezone211 <- getData('worldclim', var='bio', res=0.5, lon=150, lat=30)
climatezone30 <- getData('worldclim', var='bio', res=0.5, lon=-180, lat=0)
climatezone31 <- getData('worldclim', var='bio', res=0.5, lon=-150, lat=0)
climatezone32 <- getData('worldclim', var='bio', res=0.5, lon=-120, lat=0)
climatezone33 <- getData('worldclim', var='bio', res=0.5, lon=-90, lat=0)
climatezone34 <- getData('worldclim', var='bio', res=0.5, lon=-60, lat=0)
climatezone35 <- getData('worldclim', var='bio', res=0.5, lon=-30, lat=0)
climatezone36 <- getData('worldclim', var='bio', res=0.5, lon=0, lat=0)
climatezone37 <- getData('worldclim', var='bio', res=0.5, lon=30, lat=0)
climatezone38 <- getData('worldclim', var='bio', res=0.5, lon=60, lat=0)
climatezone39 <- getData('worldclim', var='bio', res=0.5, lon=90, lat=0)
climatezone310 <- getData('worldclim', var='bio', res=0.5, lon=120, lat=0)
climatezone311 <- getData('worldclim', var='bio', res=0.5, lon=150, lat=0)
climatezone40 <- getData('worldclim', var='bio', res=0.5, lon=-180, lat=-30)
climatezone41 <- getData('worldclim', var='bio', res=0.5, lon=-150, lat=-30)
climatezone42 <- getData('worldclim', var='bio', res=0.5, lon=-120, lat=-30)
climatezone43 <- getData('worldclim', var='bio', res=0.5, lon=-90, lat=-30)
climatezone44 <- getData('worldclim', var='bio', res=0.5, lon=-60, lat=-30)
climatezone45 <- getData('worldclim', var='bio', res=0.5, lon=-30, lat=-30)
climatezone46 <- getData('worldclim', var='bio', res=0.5, lon=0, lat=-30)
climatezone47 <- getData('worldclim', var='bio', res=0.5, lon=30, lat=-30)
climatezone48 <- getData('worldclim', var='bio', res=0.5, lon=60, lat=-30)
climatezone49 <- getData('worldclim', var='bio', res=0.5, lon=90, lat=-30)
climatezone410 <- getData('worldclim', var='bio', res=0.5, lon=120, lat=-30)
climatezone411 <- getData('worldclim', var='bio', res=0.5, lon=150, lat=-30)
#COMBINE ZONES TO CREATE ONE COMPLETE CLIMATE OBJECT
climatemosaic <- mosaic(climatezone01, climatezone02, climatezone03, climatezone04, climatezone05, climatezone06, climatezone07, climatezone08, climatezone09, climatezone010, climatezone011, climatezone10, climatezone11, climatezone12, climatezone13, climatezone14, climatezone15, climatezone16, climatezone17, climatezone18, climatezone19, climatezone110, climatezone111, climatezone20, climatezone21, climatezone22, climatezone23, climatezone24, climatezone25, climatezone26, climatezone27, climatezone28, climatezone29, climatezone210, climatezone211, climatezone30, climatezone31, climatezone32, climatezone33, climatezone34, climatezone35, climatezone36, climatezone37, climatezone38, climatezone39, climatezone310, climatezone311, climatezone40, climatezone41, climatezone42, climatezone43, climatezone44, climatezone45, climatezone46, climatezone47, climatezone48, climatezone49, climatezone410, climatezone411, fun=mean)
#EXTRACT MEAN VALUES FOR BOUNDARY POLYGONS & ATTACH TO SPDF (WEIGHT AND BUFFER OPTIONS NOT USED HERE)
gadmMEANS <- extract(climatemosaic, gadm, fun=mean, na.rm=TRUE, small=TRUE, layer=1, nl=19, sp=TRUE)