如何在 R 中将 NetCDF 文件“NDVI NOAA AVHRR”读取为栅格？

Question

我想用 R 显示 NDVI 参数，然后在每个区域中提取此参数的值。

我的文件是从以下链接下载的 NetCDF (.nc) 格式：https://www.ncei.noaa.gov/data/avhrr-land-normalized-difference-vegetation-index/access/1981/

所以我使用以下代码中的两个包“raster”和“ncdf4”在R下将第一个文件导入为“AVHRR-Land_v005_AVH13C1_NOAA-07_19810624_c20170610041337.nc”：

library(ncdf4) 
library(raster) 
setwd("path/.../data")
r=raster("AVHRR-Land_v005_AVH13C1_NOAA-07_19810624_c20170610041337.nc",varname="NDVI")

但是当应用我的程序时，我得到了这个错误：

Error in CRS(as.character(projection(crs))) : 
  no arguments in initialization list

我从下面的代码中选择我的变量名称（“NDVI”）。我认为问题出在坐标系的格式上！

library(ncdf4)    
nc <- nc_open("AVHRR-Land_v005_AVH13C1_NOAA-07_19810624_c20170610041337.nc")
attributes(nc$var)$names

你有解决这个问题的办法吗！

提前谢谢你

我的 R 版本和我的系统电脑：

R version 3.6.2 (2019-12-12)
Copyright (C) 2019 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

编辑

感谢 Robert Hijmans 的回答（以下回答）。

我更新了包（更新某些包时出现错误消息）

update.packages(ask=F)
Warning: package 'BH' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'callr' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'cli' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'DT' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'fansi' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'farver' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'gh' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'mime' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'pillar' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'plyr' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'prettyunits' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'stringi' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'vctrs' in library '/usr/local/lib/R/site-library' will not be updated
Warning: package 'foreign' in library '/usr/lib/R/library' will not be updated

并应用了您的代码，但我仍然遇到同样的错误。

r <- raster(f, varname="NDVI")
Error in CRS(as.character(projection(crs))) : 
  no arguments in initialization list.   


traceback()

No traceback available .  


sessionInfo()
R version 3.6.2 (2019-12-12)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.3 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.7.1
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.7.1

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C               LC_TIME=en_GB.UTF-8       
 [4] LC_COLLATE=en_GB.UTF-8     LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8   
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C                  LC_ADDRESS=C              
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] ncdf4_1.17   raster_3.0-7 sp_1.3-2    

loaded via a namespace (and not attached):
[1] compiler_3.6.2   rgdal_1.4-8      tools_3.6.2      yaml_2.2.0       Rcpp_1.0.3       codetools_0.2-16
[7] grid_3.6.2       lattice_0.20-38 

Answer 1

下载文件

url <- "https://www.ncei.noaa.gov/data/avhrr-land-normalized-difference-vegetation-index/access/1981/"
f <- "AVHRR-Land_v005_AVH13C1_NOAA-07_19810624_c20170610041337.nc"
if (!file.exists(f)) download.file(file.path(url, f), f, mode="wb")

使用 R 3.6.2 和更新的软件包，我得到：

library(raster)
#Loading required package: sp
r <- raster(f, varname="NDVI")
#Loading required namespace: ncdf4
r
#class      : RasterLayer 
#dimensions : 3600, 7200, 25920000  (nrow, ncol, ncell)
#resolution : 0.05, 0.05  (x, y)
#extent     : -180, 180, -89.99999, 90  (xmin, xmax, ymin, ymax)
#crs        : +init=EPSG:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
#source     : AVHRR-Land_v005_AVH13C1_NOAA-07_19810624_c20170610041337.nc 
#names      : NOAA.Climate.Data.Record.of.Normalized.Difference.Vegetation.Index 
#z-value    : 1981-06-24 
#zvar       : NDVI 

您能否运行update.packages(ask=F) 并重试？如果仍然失败，您能否在错误发生后显示traceback()，以及您的sessionInfo()？