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我正在尝试在 R 中修改和保存 netcdf 文件。我可以修改值，但似乎无法让文件保存并保留修改后的值。这是我正在做的事情：

使用 ncdf4 包打开文件

library(ncdf4)
nc=nc_open('RMinit_newvalues2017.nc', write=T)

重新分配缺失值 - 该文件有 2000 个变量，大约一半需要修改它们的缺失值，我可以成功地做到这一点：

for (i in 1:10){
   print(nc$var[[i]]$name) # use to match aaR/aaS
   test=grep("_Nums", nc$var[[i]]$name) # search for Nums, skip to next
   if (length(test) ==1){
     next
   }
   test2=grep("_ResN", nc$var[[i]]$name) # search for RN
    if (length(test2) == 1) {
      print(nc$var[[i]]$missval) # print orginal value
      print(xR$RN[which(xR$Variables==nc$var[[i]]$name)]) # print new value
      nc$var[[i]]$missval=xR$RN[which(xR$Variables==nc$var[[i]]$name)] # assign new value
      print(nc$var[[i]]$missval) # print assigned value

    } else if (length(test2) != 1) {
       print(nc$var[[i]]$missval)
       print(xS$SN[which(xS$Variables==nc$var[[i]]$name)])
       nc$var[[i]]$missval=xS$SN[which(xS$Variables==nc$var[[i]]$name)]
       print(nc$var[[i]]$missval)

    }
}

这是带注释的输出，显示它正在更改“_ResN”和“_StructN”的值：

[1] "Anchovies10_Nums" (nothing done here, next)
[1] "Anchovies10_ResN" (first replacement)
[1] 987.7794 (original value)
[1] 200.1975 (replacement value, printed after assignment)
[1] "Anchovies10_StructN" (repeat pattern...)
[1] 372.7469
[1] 75.54621
[1] "Anchovies1_Nums"
[1] "Anchovies1_ResN"
[1] 130.3665
[1] 15.67022
[1] "Anchovies1_StructN"
[1] 49.19491
[1] 5.913289
[1] "Anchovies2_Nums"
[1] "Anchovies2_ResN"
[1] 228.1891
[1] 34.30677
[1] "Anchovies2_StructN"
[1] 86.10911
[1] 12.94595
[1] "Anchovies3_Nums"

最后，我同步并关闭 nc 文件，该文件应将其保存到磁盘。但这里什么也没有发生。没有错误，一切似乎都很好，除了文件没有保存。我错过了什么？？？

nc_sync(nc)
nc_close(nc)

编辑：在循环中切换命令后，我能够保存要保存的文件。使用ncatt_put与分配nc$var[[i]]$missval=...似乎可以解决问题。我还意识到我一开始就编辑了错误的值，因为我需要_Fillvalue更改，而不是missval. 这现在有效：

for (i in 1:dim(a)[1]){
test=grep("_Nums", nc$var[[i]]$name) # search for Nums, skip to next
if (length(test) ==1){
  next
}
test2=grep("_ResN", nc$var[[i]]$name) # search for RN
if (length(test2) == 1) {
  ncatt_put(nc,a[i,1],"_FillValue", xR$RN[which(xR$Variables==nc$var[[i]]$name)])
} else if (length(test2) != 1) {
  ncatt_put(nc,a[i,1],"_FillValue", xS$SN[which(xS$Variables==nc$var[[i]]$name)])  
}
nc_sync(nc)
}
nc_sync(nc)
nc_close(nc)
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1 回答 1

1

将我的解决方案发布为仅供参考，以帮助未来的人......

我暂时解决了我的问题。仍然不确定为什么第一次尝试没有更新文件。我需要用来ncdf4::ncatt_put编辑 _FillValue 的属性并ncdf4::ncvar_put添加数据。然后nc_sync在循环内做一个帮助。

for (i in 1:length(b)){
  vv=as.numeric(b[i]) # index of ResN and StructN in entire list of nc file 'a'
  testSN=grep("_StructN", a[vv,1]) # use to select SN values
  testRN=grep("_ResN", a[vv,1]) # use to select RN values

  if (length(testRN) ==1){
    ncatt_put(nc,a[vv,1],"_FillValue", xR$RN[which(xR$Variables==a[vv,1])])
    ncvar_put(nc,a[vv,1], rep(xR$RN[which(xR$Variables==a[vv,1])],150)) # replicate 5x30
  } else if (length(testSN) ==1){
    ncatt_put(nc,a[vv,1],"_FillValue", xS$SN[which(xS$Variables==a[vv,1])])
    ncvar_put(nc,a[vv,1], rep(xS$SN[which(xS$Variables==a[vv,1])],150))
  }
  nc_sync(nc)
}
nc_sync(nc)
nc_close(nc)
于 2018-07-12T19:10:03.397 回答