Here's the (nearly) equivalent query for the statements dump[1] loaded into Blazegraph:

PREFIX wd: <http://www.wikidata.org/entity/>
SELECT DISTINCT ?city ?citylabel ?mayorlabel WHERE {
  ?city      wd:P31s/wd:P31v wd:Q515     .      # find instances of subclasses of city
  ?city      wd:P6s          ?statement  .      # with a P6 (head of goverment) statement
  ?statement wd:P6v          ?mayor      .      # ... that has the value ?mayor
  ?mayor     wd:P21s/wd:P21v wd:Q6581072 .      # ... where the ?mayor has P21 (sex or gender) female
  FILTER NOT EXISTS { ?statement wd:P582q ?x }  # ... but the statement has no P582 (end date) qualifier
 
  # Now select the population value of the ?city
  # (the number is reached through a chain of three properties)
  ?city wd:P1082s/wd:P1082v/<http://www.wikidata.org/ontology#numericValue> ?population .

  # Optionally, find English labels for city and mayor:
  OPTIONAL {
    ?city wd:P373s/wd:P373v ?citylabel .
    # FILTER ( LANG(?citylabel) = "en" )
  }
  OPTIONAL {
    ?mayor wd:P373s/wd:P373v ?mayorlabel .
    # FILTER ( LANG(?mayorlabel) = "en" )
  }

} ORDER BY DESC(?population) LIMIT 100

Free beer to anyone who can figure out how to use those language filters.  Would we need to also load property definitions[2]?

1. http://tools.wmflabs.org/wikidata-exports/rdf/exports/20150223/wikidata-statements.nt.gz
2. http://tools.wmflabs.org/wikidata-exports/rdf/exports/20150223/wikidata-properties.nt.gz

On Tue, Apr 21, 2015 at 11:13 AM, Jeremy Baron <jeremy@tuxmachine.com> wrote:

Hi,

On Tue, Apr 21, 2015 at 5:05 PM, Thad Guidry <thadguidry@gmail.com> wrote:
> We had US Census, World Bank, and UN Data as our primary data sources for any /statistics/ of a City/Town/Village.  Here's Houston - https://www.freebase.com/m/03l2n#/location/statistical_region

I don't understand where a lot of those numbers are from.

Also, maybe Houston is a bad example because the Census Bureau revised
numbers after the data was released.[0] Even some official Census
Bureau sites still report the old, pre-appeal number.[1]

There are multiple years that have duplicate conflicting values after
clicking "65 values total »" at your link. At first I was thinking it
may be something like estimates base vs. estimate vs. decennial.
However, for 2010 and 2011 there's one value that matches estimate
from [1] (source = [2]) and a larger value (source = [3]) that does
not match any other data I've seen. [2] and [3] both use the same
"Attribution URI" [4].

In any case, why take this from freebase instead of importing directly
from Census Bureau data? It's available in bulk. Format isn't great
but isn't horrible either. (at least the 5-year ACS is inconsistent
about upper/lower case for state two letter abbreviations. and, I
think, most humans would prefer something like a geoid as a key rather
than a dataset specific key used to look up the geoid in a different
file. and other quirks)

-Jeremy

[0] http://www.chron.com/news/houston-texas/houston/article/City-wins-census-appeal-count-adjusted-4087372.php
[1] http://factfinder.census.gov/bkmk/table/1.0/en/PEP/2013/PEPANNRES/1620000US4835000
[2] https://www.freebase.com/g/11x1k306j
[3] https://www.freebase.com/m/0jst35z
[4] http://www.census.gov/popest/about/terms.html

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