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我正在使用来自拉丁美洲 WorldClim V2.1（30 秒分辨率）的环境栅格图层。我希望图层具有精确的分辨率（50km2 像素大小）。但是，我有点不确定我是否按照正确的步骤来处理文件。任何有关检查过程的帮助将不胜感激。

最后一件事，我想知道 s 在terra::resample做什么NA。谢谢 ！

这是一个年平均温度的例子

图书馆

library(rnaturalearth)
library(terra)
library(sf)
library(tidyverse)

底图

# world and Latin America
world <- rnaturalearth::ne_countries(scale = 'medium', returnclass = 'sf')
bbox_Latam_unprojected <- c(xmin=-118.40137, ymin=-55.89170, xmax=-34.80547, ymax= 32.71533)
Latam_unprojected <- world %>% st_crop(bbox_Latam_unprojected)

# equal area projection (Equatorial Lambert azimuthal equal-area) 
equalareaCRS <-  '+proj=laea +lon_0=-73.125 +lat_0=0 +datum=WGS84 +units=m +no_defs'
Latam_projected <- sf::st_transform(Latam_unprojected, crs=equalareaCRS)
Latam <- st_union(Latam_projected)

# raster of Latin America to use as template - 50km^2 (50000m^2)
Latam.grid <- st_make_grid(Latam+1000, cellsize = 50000, crs = equalareaCRS) %>% 
  st_sf('geometry' = ., 'occ'= 0) 
r <- rast(res=50000, ext(vect(Latam.grid)), crs=equalareaCRS)
Latam.raster <- terra::rasterize(x = vect(Latam.grid), 
                 y = r, field = 'occ') %>% terra::mask(., vect(Latam))

环境层

# annual temperature files
url <- 'https://biogeo.ucdavis.edu/data/worldclim/v2.1/base/wc2.1_30s_tavg.zip'
download.file(url, destfile='data/wc2.1_30s_tavg')

# average annual temperature
tavg_files <- list.files('data/wc2.1_30s_tavg', '.tif', full.names=TRUE)
world_tavg <- rast(tavg_files)
tavg_unprojected <- crop(world_tavg, ext(Latam_unprojected)+1)
tavg <- project(tavg_unprojected, equalareaCRS, method='near') # reproject to equal area
tavg <- mean(tavg)
names(tavg) <- 'tavg'

# resample to Latam's preferred resolution
tavg_Latam <- terra::resample(tavg, Latam.raster, method='bilinear')

关注

class       : SpatRaster 
dimensions  : 12512, 11213, 1  (nrow, ncol, nlyr)
resolution  : 829.4488, 829.4488  (x, y)
extent      : -5009004, 4291606, -6411068, 3966996  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=laea +lat_0=0 +lon_0=-73.125 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs 
source      : tavg.tif 
name        :     tavg 
min value   :  -15.775 
max value   : 29.56667

tavg_Latam

class       : SpatRaster 
dimensions  : 199, 172, 1  (nrow, ncol, nlyr)
resolution  : 50000, 50000  (x, y)
extent      : -4409882, 4190118, -6080809, 3869191  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=laea +lat_0=0 +lon_0=-73.125 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs 
source      : memory 
name        :      tavg 
min value   : -2.684936 
max value   :  29.17986

干杯，弗洛

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