About

Python tools for querrying a data source and drawing thematic cartographic representations. Works with CSV, SHP, and other OGR based data files.

By Nathaniel Vaughn Kelso at Stamen.

Stubs out MSS and MML files compatabile with Mapnik via Cascadenik or Carto based on a dataset for:

• Quick data exploration of what's in a dataset
• Refined cartographic presentations

Bonus: Will also build a legend in HTML format displaying the colors and bin labels.

Looking for vector thematic maps in the browser instead? Try IndieMaps OpenLayers-Symbology.

Installation

Git checkout (requires git)

git clone git://github.com/nvkelso/thematic-carto-tools.git
cd thematic-carto-tools

Includes built in support for CSV/TSV and DBF/SHP files. Uses OGR for other file types.

Usage

Just a single sympol:

python thematic.py sample_data/ne_10m_admin_0_countries.shp

Classify a polygon/polyline dataset in 5 steps using the POP_EST indicator field (default is: --classification-type=quantile -n 5):

python thematic.py sample_data/ne_10m_admin_0_countries.shp POP_EST

Separate color for each feature value:

python thematic.py sample_data/ne_10m_admin_0_countries.shp MAP_COLOR --classification-type=unique-value

Will create 3 files:

1. style.mml - Cascadenik map markup layer file
2. stylesheet.mss - Cascadenik map style sheet file
3. legend.html - See the color breaks in a pretty HTML legend

These files are writen local to where you ran the script. Use the "--out_files" option to specify different names OR...

NOTE: If you only want to generate the .mss file, try this:

python thematic.py sample_data/ne_10m_admin_0_countries.shp POP_EST stylesheet.mss

Wonder what indicator to use? Use the "describe" mode to report OrgInfo style field listing:

python thematic.py sample_data/ne_10m_admin_0_countries.shp --classification-type=describe

Sample output

Legend HTML:

Styling MSS:

.ne_10m_admin_0_countries[zoom>=0][POP_EST>=-99.0]{ polygon-fill: #ffffcc; }
.ne_10m_admin_0_countries[zoom>=0][POP_EST>=72660.0]{ polygon-fill: #c2e699; }
.ne_10m_admin_0_countries[zoom>=0][POP_EST>=1533964.0]{ polygon-fill: #78c679; }
.ne_10m_admin_0_countries[zoom>=0][POP_EST>=6995655.0]{ polygon-fill: #31a354; }
.ne_10m_admin_0_countries[zoom>=0][POP_EST>=22215421.0]{ polygon-fill: #006837; }

Layers MML:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map[
    <!ENTITY epsg4326 "+proj=longlat +datum=WGS84">
    <!ENTITY epsg900913 "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs +over">
    <!ENTITY epsg900913_extent "-20037508,-20037508,20037508,20037508">
]>

<Map srs="&epsg900913;">

    <Stylesheet src="stylesheet.mss"/>

    <Layer class="ne_10m_admin_0_countries" id="ne_10m_admin_0_countries" srs="&epsg4326;">
	    <Datasource>
		    <Parameter name="type">shape</Parameter>
		    <Parameter name="file">/Users/nvkelso/github/thematic-carto-tools/sample_data/ne_10m_admin_0_countries</Parameter>
	    </Datasource>
    </Layer>

</Map>

Describe:

data source : ne_10m_admin_0_countries.shp
   full path: /Users/nvkelso/github/thematic-carto-tools/sample_data/ne_10m_admin_0_countries.shp
==== layer 0
  shape type: Polygon
  # features: 253
         srs: GEOGCS["GCS_WGS_1984",
    DATUM["WGS_1984",
        SPHEROID["WGS_1984",6378137.0,298.257223563]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]]
      extent: (-179.99978348919961, 180.0000000000001) - (-89.99982838943765, 83.63381093402974)
  # fields 31: NAME (first value)
               ------------------
               ne_10m_adm	(ABW)
               ScaleRank	(3)
               LabelRank	(6)
               FeatureCla	(Adm-0 country)
               OID_	(18)
               SOVEREIGNT	(Netherlands)
               SOV_A3	(NL1)
               ADM0_DIF	(1.0)
               LEVEL	(2.0)
               TYPE	(Country)
               ADMIN	(Aruba)
               ADM0_A3	(ABW)
               GEOU_DIF	(0.0)
               GEOUNIT	(Aruba)
               GU_A3	(ABW)
               SU_DIF	(0.0)
               SUBUNIT	(Aruba)
               SU_A3	(ABW)
               NAME	(Aruba)
               ABBREV	(Aruba)
               POSTAL	(AW)
               NAME_FORMA	(None)
               TERR_	(Neth.)
               NAME_SORT	(Aruba)
               MAP_COLOR	(9.0)
               POP_EST	(103065.0)
               GDP_MD_EST	(2258.0)
               FIPS_10_	(0.0)
               ISO_A2	(AW)
               ISO_A3	(ABW)
               ISO_N3	(533.0)

Requirements

• Python >= 2.6

• GDAL with OGR support >= 1.8.1

Author

• Nathaniel V. KELSO (nvkelso)

Contributors

• Michael Lawrence Evans (mlevans)
• Mike Migurski (migurski)

Coda

Inspired by a fall 2011 workshop held at Stamen about future of Carto and Cascadenik CSS style map rendering in Mapnik & etc.