[gdal-dev] OGR Field Types?

[Stefan Keller]

2015-05-21 23:34 GMT+02:00 Even Rouault <even.rouault at spatialys.com>:
...
>> 4. "Geometry(Easting)","Geometry(Northing)"
> For points only I guess?

Yes.

>> 5. "Geometry" -- encoded in WKT; having subtype values WKT (default),
>> Point, LineString, Polygon.
> "WKT" is not really consistant with Point,LineString,Polygon since the later
> would be expressed as WKT I guess. So perhaps WKT, WKT(Point),
> WKT(LineString), WKT(Polygon) ?

Right, d'accord. So, let's introduce following two geometry types:
* "Easting","Northing"
* WKT, WKT(Point), WKT(LineString), WKT(Polygon)

There are additional restricions to these geometry types:
* "Easting","Northing" must co-occur and should be neighboring columns
(in either order).
* if WKT is given, all rows are expected to contain the same geometry type.
* There's only one geometry column per .csvt, namely either
<<"Easting","Northing">> or <<WKT>>.

OK?

--S.


2015-05-21 23:34 GMT+02:00 Even Rouault <even.rouault at spatialys.com>:
> Le jeudi 21 mai 2015 23:17:26, Stefan Keller a écrit :
>> Hi Even
>>
>> I just see some type mod and subtype definitions for .csvt files in
>> the CSV docs [1] :
>> <<
>> In a single line the types for each column have to be listed with
>> double quotes and be comma separated (e.g., "Integer","String"). It is
>> also possible to specify explicitly the width and precision of each
>> column, e.g. "Integer(5)","Real(10.7)","String(15)". The driver will
>> then use these types as specified for the csv columns. Starting with
>> GDAL 2.0, subtypes can be passed between parenthesis, such as
>> "Integer(Boolean)", "Integer(Int16)" and "Real(Float32)"
>> <<
>>
>> Following questions and suggestions about .csvt:
>> 1. Do type names really have to be in double quotes?
> No
>> 2. Is the separator always comma or can it also be a semicolon?
> Yes, always comma
>> 3. What about a Geometry type with subtypes? I suggest to add
>> 4. "Geometry(Easting)","Geometry(Northing)"
> For points only I guess? Well you can build points with a OGR VRT from 2 CSV
> columns. I might perhaps add in some time an open option to specify the
> columns for the easting/longitude and northing/latitude.
>> 5. "Geometry" -- encoded in WKT; having subtype values WKT (default),
>> Point, LineString, Polygon.
> "WKT" is not really consistant with Point,LineString,Polygon since the later
> would be expressed as WKT I guess. So perhaps WKT, WKT(Point),
> WKT(LineString), WKT(Polygon) ?
>
>>
>> What do you think?
>> This could also make QGIS "Add Delimited Text Layer..." even better.
>>
>> --S.
>>
>> [1] http://www.gdal.org/drv_csv.html
>>
>> 2015-04-29 22:57 GMT+02:00 Stefan Keller <sfkeller at gmail.com>:
>> > Salut Even,
>> >
>> > Merci!
>> >
>> > 2015-04-29 20:35 GMT+02:00 Even Rouault <even.rouault at spatialys.com>:
>> >> Stefan
>> >>
>> >>> Questions:
>> >>> 1. How is 'binary' encoded? E.g. when defining binary in a CSV file,
>> >>> how is it encoded? Hex?
>> >>
>> >> There's no support in the CSV driver for binary data
>> >>
>> >>> 2. Can a field in a CSV input files have a IntegerList or a Binary?
>> >>
>> >> No. Well on writing, the IntegerList will be serialized as a string. But
>> >> not recognized as IntegerList on reading
>> >>
>> >>> 3. What is the value delimiter in a field of type IntegerList,
>> >>> Integer64List, RealList, StringList?
>> >>
>> >> The default serializatoin will be
>> >> (number_of_elements:val1,val2,...,valn), but currently it is truncated
>> >> to 80 chracters
>> >>
>> >>> 4. "Boolean, Int16, Float32" are mentioned as subtypes. Are there more
>> >>> subtypes?
>> >>
>> >> Not currently. See
>> >> https://trac.osgeo.org/gdal/wiki/rfc50_ogr_field_subtype
>> >>
>> >> Even
>> >>
>> >> --
>> >> Spatialys - Geospatial professional services
>> >> http://www.spatialys.com
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com