Structure of "identical" data not equal in size

*To*: mathgroup at smc.vnet.net*Subject*: [mg126915] Structure of "identical" data not equal in size*From*: Paul E McHale <paulmchale at me.com>*Date*: Sun, 17 Jun 2012 03:59:02 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

(* First, the internal data and then writing it to CSV *) m=Table[{i,Sin[i],Cos[i]},{i,1,1000,1.0}]; SetDirectory[NotebookDirectory[]] Export["Test2.csv",m, "CSV"] (*Reading it back in *) mIn = Import["Test2.csv", "CSV"] (* compare data *) mIn==m >> True (* see memory usage *) ByteCount[m] >> 24168 ByteCount[mIn] >> 144040 (* what is the minimum size using reals *) 1000 * 3 * 8 >> 24000 Actual size: 24168 Read in file data: 144040 (* Size *) ByteCount[mIn]/ByteCount[m] * 1.0 >> 5.96 -------------- Why is the "same" data taking up 6x the memory after being written to disk and read back in. This is a serious problem as we have large data at work being shared by files and Mathematica is currently the only language that can't read it (C# being the other language). How can they pass for equal yet internally generated takes much less memory? Any input welcome as I can only reduce the data with an external editor so I can try to work with it. Thanks, Paul