How to write a binary filefrom a netcdf file?

Question

I would like to write a binary file from a netcdf file

library(ncdf)
download.file("http://gswp/Fixed/SoilDepth.nc", destfile="SoilDepth.nc")
soil <- open.ncdf("SoilDepth.nc")
soil$var[[3]] -> var3 
get.var.ncdf(soil, var3) -> SoilDepth
download.file("http://gswp/Fixed/landmask_gswp.nc", destfile="landmask.nc")
landmask <- open.ncdf("landmask.nc")
landmask$var[[3]] -> varland
get.var.ncdf(landmask, varland) -> land
land = t(land)
land[land==1] <- SoilDepth
land[land==0] <- NA
land = t(land)
image(land)

the result of This code will look like:![map of soil][1]

Now I want to write it to a binary file:

The result is an image upside down.

where is the write? Also what is with all the transposing? You would benefit from working carefully at each step to get rid of unneeded code. Just use [ to reorder by rows/columns — mdsumner
– mdsumner, Commented Sep 6, 2012 at 22:23
What mdsumner probably meant was something like y <- y[nrow(y):1,] to reverse the rows of matrix y. — MvG
– MvG, Commented Sep 7, 2012 at 11:43

MvG · Accepted Answer · 2012-09-07 11:57:25Z

1

You requested a reverse orientation yourself, by specifying ylim=c(1,0). Simply change that last line to

image(y)

and you'll be fine, as the double transpose does nothing except eat resources.

Further information: The only difference between the original and the re-read data is the fact that the latter has NaN (i.e. Not a Number) in the places where the former had NA (Not Available). Undoing this modification yields completely identical data:

y[is.nan(y)] <- NA

After this, y becomes indistinguishable from land.

edited Sep 7, 2012 at 11:57

answered Sep 7, 2012 at 11:50

MvG

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