| Re: Using .evf files programmatically [message #56762] |
Tue, 13 November 2007 09:32 |
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Matt[1]
Messages: 23
Registered: December 2006
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Junior Member |
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Thanks. What is the shapefile reader? Is that the IDLffShape object
mentioned previously? Sorry if the question is inappropriate - I'm a
novice.
Matt
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| Re: Using .evf files programmatically [message #56764 is a reply to message #56762] |
Tue, 13 November 2007 08:43  |
Jean H.
Messages: 472
Registered: July 2006
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Senior Member |
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> Well, evf attributes appear to be saved in a .dbf file like they are
> for shapefiles. There's an ENVI routine to write DBF files for evf
> attributes, but there doesn't seem to be a routine to read one. So I
> am assuming they intend for you to read the dbf files using ODBC
> methods? If so, since i know next to nothing about ODBC I'd be pretty
> tempted to just forget about the evf file and go back to reading the
> shapefile directly using the IDLffShape object. You can find some
> good examples of doing that here:
>
> http://www.dfanning.com/map_tips/shapefile.html
>
> Hope that helps,
> Jeff
Similarly, you can access the evf file and use the shapefile reader to
read the dbf (only) that is associated with your evf file...
Jean
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| Re: Using .evf files programmatically [message #56774 is a reply to message #56764] |
Mon, 12 November 2007 12:40 |
Jeff N.
Messages: 120
Registered: April 2005
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Senior Member |
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On Nov 12, 2:26 pm, Matt <mmsmith1...@gmail.com> wrote:
> Hi group:
>
> Does anyone have experience accessing .evf files programatically? I am
> using an evf file that I converted from shapefile format. I use
> envi_file_query to get the coordinates for each polygon and use these
> coordinates to subset a raster image.
>
> I need to name each ouput file according to an attribute that was
> present in the original shapefile but from what I can tell it's no
> longer present in the evf file. Is there a way to access this
> information programmatically? Basically, when I extract the
> coordinates from a given evf record I need to figure out the name of
> the record so that i can name my ouptut files.
>
> Any one have experience with this?
>
> Thanks.
>
> Matt
Well, evf attributes appear to be saved in a .dbf file like they are
for shapefiles. There's an ENVI routine to write DBF files for evf
attributes, but there doesn't seem to be a routine to read one. So I
am assuming they intend for you to read the dbf files using ODBC
methods? If so, since i know next to nothing about ODBC I'd be pretty
tempted to just forget about the evf file and go back to reading the
shapefile directly using the IDLffShape object. You can find some
good examples of doing that here:
http://www.dfanning.com/map_tips/shapefile.html
Hope that helps,
Jeff
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