Re: Importing external grid file to do contour plot
- To: mathgroup at smc.vnet.net
- Subject: [mg13047] Re: Importing external grid file to do contour plot
- From: "P.J. Hinton" <paulh>
- Date: Sat, 4 Jul 1998 16:44:51 -0400
- Organization: Wolfram Research, Inc.
- Sender: owner-wri-mathgroup at wolfram.com
On 30 Jun 1998, Sophie Hon wrote:
> I'm trying to read an outside grid file into Mathematica in order to do
> a contour plot. It's a 50 by 50 grid, so that the data is arranged as
> 50 strings of 50 numbers.
> Here is what I have so far, which I know does not work:
>
> ReadList["Macintosh HD:Mathematica 3.0 Files:fish:aqc.grd",
> Array[Number,{50,50}]]
>
> I would appreciate your help very much. Sincerely,
How are the individual numbers separated in the file? This is important
information to consider when formulating a ReadList[] expression. If
you are dealing with space or tab delimited data, then the following
command should probably work:
ReadList["Macintosh HD:Mathematica 3.0 Files:fish:aqc.grd",
Number,
RecordLists -> True
]
This tells Mathematica to read the contents of the file as a list. By
default, spaces and tabs are interpreted by the kernel as separators
between numbers. The option RecordLists, when set to true, starts a
new row in the List whenever a newline character is encountered.
A more detailed discussion of this can be found in the Mathematica book.
If you have access to the online documentation, you can evaluate the
following expression in a notebook and the HelpBrowser will be opened
to the appropriate section:
FrontEndExecute[FrontEnd`HelpBrowserLookup["MainBook", "2.11.7"]]
If you are dealing with comma delimited data, things are a little more
complicated. See the FAQ at URL:
http://www.wolfram.com/support/InputOutput/ExternalFiles/CommaSeparatedData.html
for a possible solution.
--
P.J. Hinton
Mathematica Programming Group paulh at wolfram.com Wolfram
Research, Inc. http://www.wolfram.com/~paulh/
Disclaimer: Opinions expressed herein are those of the author alone.