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MathGroup Archive 2005

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Re: String to numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55397] Re: String to numbers
  • From: Maxim <ab_def at prontomail.com>
  • Date: Mon, 21 Mar 2005 03:02:04 -0500 (EST)
  • References: <d1gu3b$p0$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On Sat, 19 Mar 2005 10:15:07 +0000 (UTC), Erb, John <jerb at saint-lukes.org>  
wrote:

>
> Hello,
>
> I have data in file in the form of strings, formatted as:
>
> <2.54   3.11   2.89>
> <3.58   5.24   5.66>
> ... more
>
> How can I read this into mathematica, and convert the strings to
> numbers,
> so I would have
>
> {{2.54,3.11,2.89},{3.58,5.24,5.66},...{}}
>
> Thank you,
>
> John C. Erb
> Email:  John_C_Erb at prodigy.net
>

If we want to avoid using ToExpression, then we can do

In[1]:=
ReadList["/data1", Record,
     RecordSeparators -> {"<", ">", "\n"}] //
   ReadList[StringToStream[#], Number]& /@ #&

Out[1]=
{{2.54, 3.11, 2.89}, {3.58, 5.24, 5.66}}

but I don't understand why

ReadList["/data1", {Number, Number, Number},
   RecordSeparators -> {"<", ">", " ", "\n"}]

doesn't work. According to the description of the option NullRecords, the  
empty record terminated by "<" at the beginning of the file just should be  
skipped. Or, taking a simpler example, if the file data2 contains 1::2,  
then

ReadList["/data2", Number,
   RecordSeparators -> {":"}]

should return {1, 2} but it gives {1, $Failed}. Besides,

ReadList["/data2", Number,
   RecordSeparators -> {"::"}]

works but

ReadList["/data2", {Number},
   RecordSeparators -> {"::"}]

again reads only the first element.

Maxim Rytin
m.r at inbox.ru


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