In Intro to PL/R and R, we covered how to enable PL/R language in the database and wrote some PL/R functions
that rendered plain text reports using the R environment. What makes combining R and PostgreSQL in
PL/R most powerful is when you can start writing SQL summary queries that use R functions like any other SQL function.
In this next example, we'll be using PostGIS test runs from tests we autogenerated from the Official PostGIS documentation (Documentation Driven Testing (DDT))
as described in the Garden Test section of the PostGIS Developer wiki.
We've also updated some of our logging generator and test patterns so future results may not represent what we demonstrated in the last article.
On a side note: Among the changes in the tests was to introduce more variants of the Empty Geometry now supported by PostGIS 2.0.
Our beloved PostGIS 2.0 trunk is at the moment somewhat unstable when working with these new forms of emptiness and stuffing geometries in inappropriate places. At the moment it doesn't survive through the mindless machine gun battery of tests we have mercilessly inflicted.
It's been great fun trying to build a better dummy while watching Paul run around patching holes to make the software more dummy proof as the dummy stumbles across questionable but amusing PostGIS use cases not gracefully handled by his new serialization and empty logic.
On yet another side note, it's nice to
see that others are doing similar wonderful things with documentation. Check out Euler's comment on catalog tables
where he uses the PostgreSQL SGML documentation to autogenerate PostgreSQL catalog table comments using OpenJade's OSX to convert the SGML to XML and then XSL similar to what we did with PostGIS documentation to autogenerate PostGIS function/type comments and as a platform
for our test generator.
For our next exercises we'll be using the power of aggregation to push data into R instead of pg.spi.execute. This will make our functions far more reusable and versatile.
A basic PL/R function
For our first example we'll create a tally report similar to what we did in our Part 1, except
the tally report data will be completely defined by how we group data in our SQL queries.
CREATE OR REPLACE FUNCTION tally_report(param_row_label text, param_col_label text,
param_row_data text[], param_col_data text[])
RETURNS text AS
$$
p_break <- table(param_row_data, param_col_data)
Total <- margin.table(p_break,2)
p_total <- rbind(p_break,Total)
names(dimnames(p_total)) <- list(param_row_label,param_col_label)
reportoutput <- sprintf("%s",
paste(capture.output(ftable(p_total)) , sep ="", collapse="\r")
)
return(reportoutput)
$$ language plr;
As you can see above, you can use the named arguments directly in PL/R without any specialness. As a general convention
we like to prefix our input arguments with param_. This is just our personal convention and not dictated by PL/R or R. We do this so it doesn't conflict with other variable names we use in the function.
Using our PL/R function in SQL
PL/R seems to really dislike arrays with NULLs as inputs into functions or at least on Windows. Others on Linux have seen no problems with NULL elements in arrays, so the issue might just be limited to PL/R on windows. When we had NULLs in our array_agg, it would crash the PL/R function even when there was nothing in the function. The problem is being investigated.
Now we can use our function by writing an SQL statement:
SELECT
tally_report(func, 'timings(ms)',
array_agg(g1),
array_agg(
COALESCE(
CAST(date_part('epoch', age(log_end,log_start))*1000 As text),
'F')
)
) As basic_tally
FROM postgis_garden_log
WHERE func LIKE 'ST_3D%'
AND g1 NOT LIKE '%Empt%'
AND g2 NOT LIKE '%Empt%'
AND g1 NOT LIKE '%NULL%'AND g2 NOT LIKE '%NULL%'
GROUP BY func
ORDER BY func;
Our example uses the array_agg function introduced in PostgreSQL 8.4 so will not work on lower versions of PostgreSQL. The output of our query
looks like:
timings(ms)
ST_3DClosestPoint 0 15 16 F
CIRCULARSTRING 0 0 0 27
CURVEPOLYGON 0 0 0 27
GEOMETRYCOLLECTIONM 0 0 0 27
GEOMETRYCOLLECTIONZ 0 0 0 27
LINESTRING 6 0 0 21
LINESTRINGM 5 1 0 21
LINESTRINGZ 6 0 0 21
MULTILINESTRING 4 1 1 21
MULTILINESTRINGM 6 0 0 21
MULTILINESTRINGZ 3 0 3 21
MULTIPOINT 8 2 2 15
MULTIPOINTM 12 0 0 15
MULTIPOINTZ 11 1 0 15
MULTIPOLYGON 0 0 0 27
MULTIPOLYGONM 0 0 0 27
MULTIPOLYGONZ 0 0 0 27
MULTISURFACE 0 0 0 27
POINT 11 0 1 15
POINTM 8 2 2 15
POINTZ 10 2 0 15
POLYGON 0 0 0 27
POLYGONM 0 0 0 27
POLYGONZ 0 0 0 27
POLYGONZM 0 0 0 27
POLYHEDRALSURFACE 0 0 0 27
TIN 0 0 0 27
TRIANGLE 0 0 0 27
Total 90 9 9 621
timings(ms)
ST_3DDFullyWithin 0 15 16 F
CIRCULARSTRING 0 0 0 27
CURVEPOLYGON 0 0 0 27
GEOMETRYCOLLECTIONM 0 0 0 27
GEOMETRYCOLLECTIONZ 0 0 0 27
LINESTRING 6 0 0 21
LINESTRINGM 5 1 0 21
LINESTRINGZ 5 1 0 21
MULTILINESTRING 5 0 1 21
MULTILINESTRINGM 4 2 0 21
MULTILINESTRINGZ 6 0 0 21
MULTIPOINT 9 3 0 15
MULTIPOINTM 10 2 0 15
MULTIPOINTZ 12 0 0 15
MULTIPOLYGON 0 0 0 27
MULTIPOLYGONM 0 0 0 27
MULTIPOLYGONZ 0 0 0 27
MULTISURFACE 0 0 0 27
POINT 11 1 0 15
POINTM 9 1 2 15
POINTZ 10 0 2 15
POLYGON 0 0 0 27
POLYGONM 0 0 0 27
POLYGONZ 0 0 0 27
POLYGONZM 0 0 0 27
POLYHEDRALSURFACE 0 0 0 27
TIN 0 0 0 27
TRIANGLE 0 0 0 27
Total 92 11 5 621
:
:
We can reuse this same function to give us a tally of the kinds of geometry companions that are supported by these functions with:
SELECT
tally_report(func, 'supported',
array_agg(g1),
array_agg(
CASE WHEN log_end IS NOT NULL THEN g2 ELSE 'F' END
)
) As basic_tally
FROM postgis_garden_log
WHERE func LIKE 'ST_3D%Distance'
AND g1 NOT LIKE '%Empt%'
AND g2 NOT LIKE '%Empt%'
AND g1 NOT LIKE '%NULL%'AND g2 NOT LIKE '%NULL%'
GROUP BY func
ORDER BY func;
supported F LINESTRING LINESTRINGM LINESTRINGZ MULTILINESTRING MULTILINESTRINGM MULTILINESTRINGZ MULTIPOINT MULTIPOINTM MULTIPOINTZ POINT POINTM POINTZ
ST_3DDistance
CIRCULARSTRING 27 0 0 0 0 0 0 0 0 0 0 0 0
CURVEPOLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
GEOMETRYCOLLECTIONM 27 0 0 0 0 0 0 0 0 0 0 0 0
GEOMETRYCOLLECTIONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
LINESTRING 21 0 0 0 0 0 0 1 1 1 1 1 1
LINESTRINGM 21 0 0 0 0 0 0 1 1 1 1 1 1
LINESTRINGZ 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRING 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRINGM 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRINGZ 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTIPOINT 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOINTM 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOINTZ 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTIPOLYGONM 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTIPOLYGONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTISURFACE 27 0 0 0 0 0 0 0 0 0 0 0 0
POINT 15 1 1 1 1 1 1 1 1 1 1 1 1
POINTM 15 1 1 1 1 1 1 1 1 1 1 1 1
POINTZ 15 1 1 1 1 1 1 1 1 1 1 1 1
POLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONM 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONZM 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYHEDRALSURFACE 27 0 0 0 0 0 0 0 0 0 0 0 0
TIN 27 0 0 0 0 0 0 0 0 0 0 0 0
TRIANGLE 27 0 0 0 0 0 0 0 0 0 0 0 0
Total 621 6 6 6 6 6 6 12 12 12 12 12 12
supported F LINESTRING LINESTRINGM LINESTRINGZ MULTILINESTRING MULTILINESTRINGM MULTILINESTRINGZ MULTIPOINT MULTIPOINTM MULTIPOINTZ POINT POINTM POINTZ
ST_3DMaxDistance
CIRCULARSTRING 27 0 0 0 0 0 0 0 0 0 0 0 0
CURVEPOLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
GEOMETRYCOLLECTIONM 27 0 0 0 0 0 0 0 0 0 0 0 0
GEOMETRYCOLLECTIONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
LINESTRING 21 0 0 0 0 0 0 1 1 1 1 1 1
LINESTRINGM 21 0 0 0 0 0 0 1 1 1 1 1 1
LINESTRINGZ 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRING 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRINGM 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTILINESTRINGZ 21 0 0 0 0 0 0 1 1 1 1 1 1
MULTIPOINT 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOINTM 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOINTZ 15 1 1 1 1 1 1 1 1 1 1 1 1
MULTIPOLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTIPOLYGONM 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTIPOLYGONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
MULTISURFACE 27 0 0 0 0 0 0 0 0 0 0 0 0
POINT 15 1 1 1 1 1 1 1 1 1 1 1 1
POINTM 15 1 1 1 1 1 1 1 1 1 1 1 1
POINTZ 15 1 1 1 1 1 1 1 1 1 1 1 1
POLYGON 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONM 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONZ 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYGONZM 27 0 0 0 0 0 0 0 0 0 0 0 0
POLYHEDRALSURFACE 27 0 0 0 0 0 0 0 0 0 0 0 0
TIN 27 0 0 0 0 0 0 0 0 0 0 0 0
TRIANGLE 27 0 0 0 0 0 0 0 0 0 0 0 0
Total 621 6 6 6 6 6 6 12 12 12 12 12 12
PostGIS in Action
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Tracked: Dec 20, 12:11