Re: Mathematica function writing for data analysis at Gould Academy

*To*: mathgroup at smc.vnet.net*Subject*: [mg35742] Re: Mathematica function writing for data analysis at Gould Academy*From*: Peter <petsie at arcor.de>*Date*: Sun, 28 Jul 2002 03:32:24 -0400 (EDT)*References*: <ahr0u6$l2l$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Charles H. Dresser wrote: > Hello, > I work at Gould Academy and have recently taught myself some of the > Mathematica scripting language. It has been my job to write functions > which will make analyzing data in Mathematica simpler for the > students. I have written a number of scripts which find different > regressions of data within a file easily. But, a couple of the > functions that I have written are not doing exactly what I want them > to do. One of them takes the input from a file with multiple columns > and what number columns the user wants to be included in the data as > ordered pairs and is suppose to output the ordered pairs which was > selected. What it does is it doesn't output anything but does set list > equal to the data which it should output. This is the code I have > written (Sorry If It Is Ugly): > > f is a filename x is the column which is wanted to be the x value in > the order pairs y is the y value which is wanted to be the ordered > pairs. > > MultCol[f_, x_, y_] := > Do[For[i = 1; list = {}; length = Length[Import[f, "Table"]], i <= > length, > i++, > list = > Append[list, {Part[Part[Import[f, "Table"], i], x], > Part[Part[Import[f, "Table"], i], y]}]] > MultColCleanUp[], {1}] > > MultColCleanUp[] := > If[DigitQ[StringTake[ToString[First[list]], {2}]], list = list, > list = Rest[list]] >(...) MultCol[f_,x_,y_]:= Select[ Import[f, "Table"][[All, {x, y}]], NumberQ[First[#]]& ] should work. If you want to keep your Functions, you should consider using local variables: MultCol[f_,x_,y_]:=Module[{list,i}, Do[...]; list] but in my opinion it is bad style (sorry), to read the file 2*length times. To assign the result to the global variable list do: list = MultCol[f,2,5]. Regards, Peter -- u will c how to mail me...