Re: Export, Import, Convert Types Again?
- To: mathgroup at smc.vnet.net
- Subject: [mg57214] Re: [mg57193] Export, Import, Convert Types Again?
- From: Clifford Martin <camartin at snet.net>
- Date: Sat, 21 May 2005 02:39:27 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Lee,
I do something similar. I import data from Excel into
Mathematica then create my functions, etc. inside
Mathematica. Then I save the whole session using
DumpSave. This maintains my data, my functions, etc.
If I want to view stuff with outside programs I Export
similarly to what you did but don't try to reimport
that data. I continue to use my DumpSave file. Works
fairly well.
Cliff
--- Lee Newman <leenewm at umich.edu> wrote:
> Q: What is the (best) way to save a big expression
> of data to be used
> later in the same notebook without having to do type
> conversion processing?
>
> Situation:
>
> 1) I have a notebook that imports data from various
> Excel spreadsheets
> and converts the data to the desired types. When
> complete, I "save" the
> expression containing the data using Export, i.e,
> Export["featureDB.tsv", "TSV"]. I do this so I
> don't have to re-process
> the data everytime I do analysis on it in this
> notebook.
>
> 2) When I open the noteobook again, I import the
> data using the
> statement: featureDB = Import["featureDB.tsv"]
>
> Problem:
> Many of type conversions that I took the time to
> process are lost.
> Using Head /@ featureDB[[1]] before and after the
> export/re-import, the
> types are as follows:
>
> Before: {Integer, Integer, List, List, List,
> Integer, List, List,
> Symbol, List}
> After : {Integer, Integer, String, String, String,
> Integer, String,
> String, String, String}
>
> So it seems that lists become Strings as Symbols
> (e.g. True, False,
> Null). I use Export so I can view the data outside
> Mathematica using a text
> editor -- should I use Save instead? Is there
> another Export format
> that will preserve mathematica expressions like
> lists upon Import?
>
> Thanks,
> Lee
>
>
>
>
>