Re: exporting numerical data

*To*: mathgroup at smc.vnet.net*Subject*: [mg106686] Re: exporting numerical data*From*: Albert Retey <awnl at gmx-topmail.de>*Date*: Thu, 21 Jan 2010 04:51:58 -0500 (EST)*References*: <hj6qea$8q2$1@smc.vnet.net>

Am 20.01.2010 12:46, schrieb: > Hi, > > I have the following problem: > I've created a table in mathematica that looks like this: > TabIntegral={ {{m_1,k_1,F(m_1,k_1)},{m_1,k_2,F(m_1,k_2)},... > {m_1,k_N,...,F(m_1,k_N)}} , {{m_2,k_1,F(m_2,k_1)},{m_2,k_2,F > (m_2,k_2)},...,{m_2,k_N,F(m_2,k_N)}} , ... , {{m_N,k_1,F(m_N,k_1)}, > {m_N,k_2,F(m_N,k_2)},...,{m_N,k_N,F(m_N,k_N)}} }; > So something like an array of {x,y,F(x,y)} records. Now, I'd like to > save this in human readable form in a file in such a way that I'd have > three columns: > m_1 k_1 F(m_1,k_1) > m_1 k_2 F(m_1,k_2) > ... > m_1 k_N F(m_1,k_N) > m_2 k_1 F(m_2,k_1) > ... > m_2 k_N F(m_2,k_N) > ... > m_N k_N F(m_N,k_N) > > I've tried like that: > Export["TabIntegral.dat", TabIntegral, "Table"] > but I got smth like this: > {0, 0, 5.641587818867172*^-9} {0, 0.2271979480396873, > 5.6073615530027356*^-9} {0, 0.4543958960793746, > 5.503771348500282*^-9}... > which is definitely not what I need. So now I guess my question is > clear, how can I get what I need? you need to get rid of one level of lists, Flatten will help to do that, like so: data = Table[{x, y, Exp[-20*x*y]}, {x, 0., Pi, Pi/5.}, {y, 0., Pi, Pi/5.}] Export[FileNameJoin[{$HomeDirectory, "Desktop", "tst.dat"}], Flatten[data, 1], "Table"] > The second question would be the following: as you see I have in my > file small numbers such like 5.6073615530027356*^-9 that I'd like to > read later on with a C-written program. If I'll leave it in this > format as it is, there's no way C-program can read that. So how to > write/format such small numbers while exporting to guarantee that I'll > be able to C-read them later? that is slightly more complicated, you could try something like this, but there might be other and better possibilities: Export[ FileNameJoin[{$HomeDirectory, "Desktop", "tst.dat"}], StringJoin[ Riffle[Map[ Function[row, Riffle[ToString[CForm[#]] & /@ row, "\t"]], Flatten[data, 1]], "\n"]], "Text" ] hth, albert