Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: how to partition a list

• To: mathgroup at smc.vnet.net
• Subject: [mg117357] Re: how to partition a list
• From: Chris Degnen <degnen at cwgsy.net>
• Date: Wed, 16 Mar 2011 06:26:20 -0500 (EST)
• References: <ilksc4$69u$1@smc.vnet.net> <201103141158.GAA07823@smc.vnet.net> <ilnhfj$odp$1@smc.vnet.net>

On Mar 15, 11:10 am, Ted Sariyski <tsari... at craft-tech.com> wrote:
> Hi,
> I have data with the following structure:  the first element is the
> number of variables.  For each variable follow:  
> title,x_var,y_var,dummy,number of points, {points}. I want to extract
> data for each variable. Coming from Fortran I tend to make a Do-cycle,
> count for the current position and assign values one by one. Is there a
> better approach to this problem?
> Thanks,
> --Ted
>
> data={{3}, {"T", "vs.", "Distance", "for", "part", 4}, {"Distance"},
> {"T"}, {1}, {5}, {0, 300.006}, {5,  300.006}, {10, 300.006}, {15,
> 300.006}, {20, 300.006},
> {"P", vs.", "Distance", "for", "part", 4}, {"Distance"}, {"P"}, {1},
> {6}, {0, 1.00007}, {5, 1.00007}, {10, 1.00007}, {15, 1.00007}, {20,
> 1.00007}, {25, 1.00007},
> {"CO2","vs.", "Distance", "for", "part", 4}, {"Distance"}, {"CO2"}, {1},
> {7}, {0, 0.000326099}, {5, 0.000326099}, {10, 0.000326099}, {15,
> 0.000326099}, {20, 0.000326099}, {25, 0.000326099}, {30, 0.000326099}}


Some pointers here.  First step is to restructure your data:

data = {{3}, {"T", "vs.", "Distance", "for", "part",
    4}, {"Distance"}, {"T"}, {1}, {5}, {0, 300.006`}, {5,
    300.006`}, {10, 300.006`}, {15, 300.006`}, {20, 300.006`}, {"P",
    "vs.", "Distance", "for", "part",
    4}, {"Distance"}, {"P"}, {1}, {6}, {0, 1.00007`}, {5,
    1.00007`}, {10, 1.00007`}, {15, 1.00007`}, {20, 1.00007`}, {25,
    1.00007`}, {"CO2", "vs.", "Distance", "for", "part",
    4}, {"Distance"}, {"CO2"}, {1}, {7}, {0, 0.000326099`}, {5,
    0.000326099`}, {10, 0.000326099`}, {15, 0.000326099`}, {20,
    0.000326099`}, {25, 0.000326099`}, {30, 0.000326099`}};

nrecords = data[[1, 1]];
data2 = Rest[data];
output = {}; Do[(title = data2[[1]];
  xvar = data2[[2, 1]];
  yvar = data2[[3, 1]];
  npts = data2[[5, 1]];
  pts = data2[[6 ;; 6 + npts - 1]];
  AppendTo[output, {title, xvar, yvar, pts}];
  data2 = Drop[data2, 5 + npts]), {nrecords}];

numberofrecords = Length[output];
Print["Number of records = " <> ToString[numberofrecords]];
yvars = output[[All, 3]];
Print[StringJoin["Y variables = ", Riffle[yvars, ", "]]];
numbersofpoints = Length /@ output[[All, 4]];
Print[StringJoin["Number of points in records = ",
   Riffle[ToString /@ numbersofpoints, ", "]]];
lastpoint = output[[3, 4, 7]];
Print["Last point in last record = " <> ToString[lastpoint]];

• References:
  • Re: Export strings to .pdf
    • From: Yves Klett <yves.klett@googlemail.com>