Re: Obtaining Random LIne from A file

*To*: mathgroup at smc.vnet.net*Subject*: [mg129880] Re: Obtaining Random LIne from A file*From*: Dana DeLouis <dana01 at icloud.com>*Date*: Thu, 21 Feb 2013 05:45:41 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

> Block[{i = RandomInteger[{1, n}], str = OpenRead[file], res}, > Skip[str, "String", i]; > res = Read[str, Expression]; Hi. I can't test this, but does this command work? (* Set pointer to line 100 *) SetStreamPosition[str, 100] I'm on a Mac, and working with file locations is a little difficult for me. I seem to remember testing this with Windows a long time ago, but I most likely am wrong. Good Luck. :>) = = = = = = = = = = HTH :>) Dana DeLouis Mac & Mathematica 9 = = = = = = = = = = On Saturday, February 16, 2013 1:07:57 AM UTC-5, Ramiro Barrantes wrote: > Hello, > > > > I would like to get a random line from a file, I know this can be done > > with Mathematica but I am playing with using sed to see if it goes > > faster, say I want to get line 1000 > > > > In mathematica it would be: > > > > <<"! sed -n p1000 filename.txt" > > > > However, I am trying to put the filename as a variable, say > > > > filename="hugefile.txt" > > > > cmd="! sed -n p1000 "<>filename > > <<cmd > > > > does not work. > > > > How can I do this? > > > > Lastly, I am getting a randomline using mathematica doing: > > > > getRandomLine[file_, n_] := > > Block[{i = RandomInteger[{1, n}], str = OpenRead[file], res}, > > Skip[str, "String", i]; > > res = Read[str, Expression]; > > Close[str]; > > res[[2]] > > ] > > > > However, it is very slow so I was going to try with sed.Any suggestions? > > > > Thanks in advance, > > Ramiro