On 10/23/12 12:17, Virgil Stokes wrote: > On 23-Oct-2012 18:09, Tim Chase wrote: >>> Finally, to my question --- What is a fast way to write these >>> variables to an external file and then read them in >>> backwards? >> Am I missing something, or would the fairly-standard "tac" >> utility do the reversal you want? It should[*] be optimized to >> handle on-disk files in a smart manner. > Not sure about "tac" --- could you provide more details on this > and/or a simple example of how it could be used for fast reversed > "reading" of a data file?
Well, if you're reading input.txt (and assuming it's one record per line, separated by newlines), you can just use tac < input.txt > backwards.txt which will create a secondary file that is the first file in reverse order. Your program can then process this secondary file in-order (which would be backwards from your source). I might have misunderstood your difficulty, but it _sounded_ like you just want to inverse the order of a file. -tkc -- http://mail.python.org/mailman/listinfo/python-list