What is the "D" type?

[jxb5000]

For PyShp, what is the meaning of the "D" type for fields in a .dbf file?

 

"D" for "double" or "D" for "date"?

 

If "D" is for "date", what is the proper type to use for a double-precision floating point number?

 

Thanks.

[Joel Lawhead]

It's "date" stored in 8 bytes.  Although it's part of the dbf spec you may find that different GIS software and libraries handle it differently.  

Here's the format from the spec:

Date in format YYYYMMDD. A date like 0000-00- 00 is *NOT* valid.

Reference:

http://www.clicketyclick.dk/databases/xbase/format/data_types.html

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[jxb5000]

Thanks, Joel.

So what is type for a double-precision floating point number?  Is it "N"?

[Joel Lawhead]

If I remember correctly it's "F" as in float.

This should work:

import shapefile

w=shapefile.Writer(shapefile.POINT)

w.point(90.3, 30)

w.field('TEMP','F','8')

w.record("50.89")

w.save("float_example")

However I have a feeling the pyshp code doesn't try to do any casting or validation when reading or writing. So anything you put in there might not throw an error until you open it in something else.

I just ran the above sample and Microsoft Excel recognized the 50.89 correctly.

- Joel

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[jxb5000]

Yes, the "F" works.  Thanks!

On Thursday, May 9, 2013 9:23:48 AM UTC-4, jxb5000 wrote: