[R-sig-Geo] reading select values from a binary file

[Barry Rowlingson]

On Wed, Dec 9, 2009 at 4:58 PM, Jonathan Thayn <jthayn at ilstu.edu> wrote:
> Hopefully there is a simple solution to this problem. I process really large satellite images in R and, in order to not offend the memory-limitation demi-gods, I open each row of the imagery one at a time, process it, write the results, and then open the next line. I use readBin() to open each line.  For examaple, say I have the following file:
>
> writeBin(1:20,con="desktop/temp.bip",size=2,endian="big")
>
> which I can open using readBin():
>
> readBin("desktop/temp.bip","integer",size=2,endian="big",n=20)
>
> Now I want to open select values from the binary file, not a complete line.  Say I want to read values 3, 7, and 10, process them, write the result, and then read values 4, 5, and 17.  How do I direct readBin to those specific values? Thanks.

 You need to seek help. Or help(seek). Yes really.

Barry


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