Stupid Geo Tricks

For Python* Developers

*(or Python-friendly)

make your dev-life better
with geojson

good for web
good for interchange
yay, standards

A Pythonista's BFF: __geo_interface__

JSONify spatial objects
Community standard
Implemented by all your favorite libraries

With __geo_interface__ in your toolbox, as long as you can read spatial data, you can write GeoJSON

Like pyshp?


import shapefile

def features(data):
  sf = shapefile.Reader(data)
  fields = sf.fields[1:]
  field_names = [field[0] for field in fields]

  for r in sf.shapeRecords():
    attr = dict(zip(field_names, r.record))
    geom = r.shape.__geo_interface__
    yield dict(geometry=geom, properties=attr)

>>> my_features = features(my_awesome_shapefile.shp)
>>> my_features.next()
# start with a shapefile, end with a geoJSON representation of each feature

See also: Shapely, fiona, mapnik... even arcpy*
*for practical purposes, in 10.2+ only

Python + pipelines
for fun & profit

Unix pipelines for regular people:


	$ cat my_awesome_document.txt | wc -l

	# returns number of lines in my_awesome_document.txt

(Feel free to just smile & nod here)

Unix pipelines for geo people:


	$ fio cat my_awesome_shapefile.shp | wc -l

	# returns number of spatial features in my_awesome_shapefile.shp

WAT.

MORE MAGIC


	$ fio cat my_red_shapefile.shp my_blue_shapefile.shp \
	  | fio load my_purple_shapefile.shp

joins two shapefiles together and creates a new shapefile


	$ fio cat boring_shapefile.shp | magical_geoprocessing_script.py \
	  | fio load shiny_new_shapefile.shp

Pipe arbitrary input through Python scripts & save the output as new spatial data

What is that?!

Python library fiona's built-in CLI "fio"
fio's cat works like unix-y cat, with added spatial goodness

(For the raster nerds, check out Rasterio, which has a CLI "rio")

Version control: just do it

Why?

You're a developer. You use source control already*.

Stick spatial data in a repo for the same reason you do it to your code.

*(right?)

How:

~~GeoGit~~ GeoGig

Git for shapefiles & databases.


	$ geogig init
	$ geogig import my_awesome_shapefile.shp
	$ geogig add
	$ geogig commit -m "initial commit"
	$ geogig status
	  On branch master
	  # blah blah etc... 
	  # basically the git we all know & love... PLUS SPATIAL.

Keep on eye on them. Start playing around now.

MORE MAGIC:

GeoJSON + GitHub

Push a GeoJSON file to GitHub.
View your GeoJSON file on GitHub.
There is no step three.

Good:
track data's history

Better:
Maps rendered automagically

Best:
Spatial diffs on GitHub

omgwtf github are you a wizard

Thanks!

slides.sarasafavi.com/geotricks

sayhi@sarasafavi.com