RE: selecting columns from a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg47876] RE: [mg47844] selecting columns from a list*From*: David.Annetts at csiro.au*Date*: Thu, 29 Apr 2004 03:06:03 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi Edo, > I just started with mathematica, wanted to load a comma > separated data > file and drop the first two columns. So I did > data=Import["C:\Data\filename.ext","CSV"]; to get the file into a > variable "data", then I am stuck, after doing some reading in > the help > files about Drop, Partition, Take. ... etc > could someone tell me what to read and where to find info > about indexing > different data structures Both the online help (Part is the section you're after) and Ruskeepaa's book are good places to start. Given the commands to load the file ... SetDirectory["c:/tmpfiles"] csv = Import["2101.csv", "CSV"]; This reads data into an array. We can get an element of this array using line05col06 = csv[[5, 6]] The first line is given by l01 = csv[[1]] (or First[csv]) The first column, by c01 = #[[1]] & /@ csv The 5th column by c05 = #[[5]] & /@ csv We can take a combination using crd = Take[csv[[#]], {4, 6}] & /@ Range[Length@csv] In the last case, I've taken columns 4, 5 & 6 from each line in the file. Regards, Dave. ========================================== Dr. David Annetts EM Modelling Analyst CSIRO DEM Tel: +612 9490 5416 North Ryde Fax: +612 9490 5467 Australia David.Annetts at csiro.au ===========================================