* Even Rouault <[email protected]> [2017-11-22 14:30:23 +0100]:

On mercredi 22 novembre 2017 14:14:38 CET Nikos Alexandris wrote:
* Even Rouault <[email protected]> [2017-11-20 15:59:51 +0100]:
>On lundi 20 novembre 2017 15:48:20 CET Nikos Alexandris wrote:
>> * Even Rouault <[email protected]> [2017-11-07 22:37:02 +0100]:
>> >> 2. Is OGR handling well the conversion from .osm to ESRI Shapefiles?
>> >
>> >Yes, but within the limits ot the shapefile, and particularly .dbf
>> >format:
>> >limitation to 254 characters for field values, 10 characters for field
>> >names... which are easily violated by OSM extracts.
>> >
>> >Spatialite, GeoPackage, PostGIS etc. would be better choices as output
>> >format>
>> >
>> >> 3. What is the way to split "other_tags" in multiple new fields *when*
>> >> knowing exactly which tags are contained and should be obtained?
>> >
>> >Edit osmconf.ini to add in the attributes= settings the tag names you're
>> >interested in.
>> >
>> >Even
>>
>> Dear List,
>>
>> in a custom .ini file, under the [points] layer, an `attributes=`
>> instruction set of values that includes `natural,cave_entrance` (key and
>> value under OSM's Natural key), well extracts for the points layer some
>> existing nodes which bear the tag `natural:cave_entrance`.
>>
>> It is not required, as far as I understand the documentation, to include
>> both the parent key and any values (under it) of interest. Perhaps it may
>> be practical to have the attributes of interest split in a separate
>> column.
>>
>> The command I tested, for example, is:
>>
>> ```
>> ogr2ogr --config OSM_CONFIG_FILE custom.ini -f SQLite -dsco
>> SPATIALITE=YES
>> -gt 65536 -progress output.sqlite source.osm ```
>>
>> While this is sufficient for the work I am doing (I can filter
>> `cave_entrance`s out from the `natural` column in the `output.sqlite`
>> file), I wonder why the entries for some nodes correctly bear the string
>> `cave_entrance` in the `natural` column, yet the `cave_entrance` column
>> itself is empty for the same entries.
>
>The attributes keyword in osmconf.ini will select OSM tags whose *key* is
>one of the item specified in attributes.
>If you want to filter by value, you may add a -where or -sql clause  with
>something like "natural = 'cave_entrance'"

This works!

Yet, I can't seem to find an answer on the web, nor a solution by trying.
I'd like to perform SQL queries in one go: one querying the points layer
and another one the lines layer.

This is certainly not a JOIN operation, as far as I understand. And
UNION only works in data sourced from the same table/layer. Is it doable
to merge an

SELECT *
FROM points
WHERE ...

and an

SELECT *
FROM lines
WHERE ...

query?

You can't do that in a single operation with ogr2ogr. You may use ogr2ogr for 
each layer, with
-append if you need to append to an existing output file

Or if you want to do in a single operation. You can use a OGR VRT
( http://gdal.org/drv_vrt.html ) file like the following one (customize the 
name of the
datasource and the SQL expressions) as the input file of ogr2ogr

<OGRVRTDataSource>
 <OGRVRTLayer name="points">
   <SrcDataSource relativeToVRT="1" shared="0">in.osm</SrcDataSource>
   <SrcSQL>SELECT * FROM points</SrcSQL>
   <GeometryType>wkbPoint</GeometryType>
   <LayerSRS>WGS84</LayerSRS>
 </OGRVRTLayer>
 <OGRVRTLayer name="lines">
   <SrcDataSource relativeToVRT="1" shared="0">in.osm</SrcDataSource>
   <SrcSQL>SELECT * FROM lines</SrcSQL>
   <GeometryType>wkbLineString</GeometryType>
   <LayerSRS>WGS84</LayerSRS>
 </OGRVRTLayer>
 <OGRVRTLayer name="multilinestrings">
   <SrcDataSource relativeToVRT="1" shared="0">in.osm</SrcDataSource>
   <SrcSQL>SELECT * FROM multilinestrings</SrcSQL>
   <GeometryType>wkbMultiLineString</GeometryType>
   <LayerSRS>WGS84</LayerSRS>
 </OGRVRTLayer>
 <OGRVRTLayer name="multipolygons">
   <SrcDataSource relativeToVRT="1" shared="0">in.osm</SrcDataSource>
   <SrcSQL>SELECT * FROM multipolygons</SrcSQL>
   <GeometryType>wkbMultiPolygon</GeometryType>
   <LayerSRS>WGS84</LayerSRS>
 </OGRVRTLayer>
 <OGRVRTLayer name="other_relations">
   <SrcDataSource relativeToVRT="1" shared="0">in.osm</SrcDataSource>
   <SrcSQL>SELECT * FROM other_relations</SrcSQL>
   <GeometryType>wkbGeometryCollection</GeometryType>
   <LayerSRS>WGS84</LayerSRS>
 </OGRVRTLayer>
</OGRVRTDataSource>

Magnifique!  Both work as expected.


Some bash functions:

For a single operation, given a custom osmconf.ini file

# Syntax: osm2sqlite  INI-FILE  SQL-CLAUSE  SOURCE.OSM
# Reusing parts from INI and SQL filenames for the output file
function osm2sqlite { ogr2ogr --config OSM_CONFIG_FILE $1 -sql @"$2" -f SQLite 
-dsco SPATIALITE=YES -gt 65536 -progress $(basename $3 .osm)_$(basename $1 
.ini)_${2#*.}.sqlite $3; };


For two operations

# First filtering
# Syntax: osm2sqlite  INI-FILE  SQL-CLAUSE  SOURCE.OSM
function osm2sqlite { ogr2ogr --config OSM_CONFIG_FILE $1 -sql @"$2" -f SQLite 
-dsco SPATIALITE=YES -gt 65536 -progress $(basename $3 .osm)_$(basename $1 .ini).sqlite 
$3; };

# Filter and append to output file of the above command, given the same source 
file is used
# Syntax: osm2sqlite.append  INI-FILE  SQL-CLAUSE  SOURCE.OSM
function osm2sqlite.append { ogr2ogr -append --config OSM_CONFIG_FILE $1 -sql 
@"$2" -f SQLite -dsco SPATIALITE=YES -gt 65536 -progress $(basename $3 
.osm)_$(basename $1 .ini).sqlite $3; };


Similar for the VRT file, just skipping the '-sql' part. For
completeness, I kept only points and lines in the VRT file, since I am
not interested, at the moment, for the rest of the features.

Merci Even u. Danke Frank,

Nikos

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