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Synchronisation and Assimilation

Joshua Powell joshuapowell

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Synchronisation and Assimilation
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@joshuapowell
joshuapowell / 05020005.geojson
Created July 17, 2015 15:07
Lower Monongahela Watershed -- 05020005
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@joshuapowell
joshuapowell / result.geojson
Last active August 29, 2015 14:24
Dissolve all HUC 12 Polygons into a single HUC 6 Polygon
SELECT
huc_6_name,
ST_AsGeoJson(ST_Multi(ST_Union(CAST(t.geometry AS Geometry)))) as huc_6_dissovled
FROM
territory AS t
WHERE
huc_6_name = 'Potomac'
GROUP BY
huc_6_name
@joshuapowell
joshuapowell / gist:960611516647012fceb3
Last active August 29, 2015 14:23
Associate Report with HUC in WaterReporter
SELECT
r.id AS report_id,
t.id AS territory_id,
t.huc_12_name,
t.huc_10_name,
t.huc_8_name,
t.huc_6_name
FROM
territory t,
report r
CREATE EXTENSION postgis;
If this fails to run make sure GDAL is installed:
apt-get install gdal-bin
@joshuapowell
joshuapowell / gist:1fb8f9feff0a3e607c8c
Last active March 9, 2021 20:07
Import Millions of Features Into Mapbox

Import Millions of Features Into Mapbox

This tutorial assumes you have either a SHP file or GeoJSON file with your data ready to go and project at WGS1984 (i.e., 4326). It also assumes you are operating under a Unix environment.

Prerequisites

  1. OGR
  2. Brew
  3. Tippecanoe
  4. Mapbox.com Account
@joshuapowell
joshuapowell / Tutorial
Last active August 29, 2015 14:11
Creating high density (1M+ Map Markers) map using a SHP file and Mapbox.com
## Convert your SHP File to a GeoJSON File
1. Download and Unzip your SHP file
2. Change to the SHP file directory
3. Convert the SHP file to a GeoJSON file
````
ogr2ogr -f "GeoJSON" my_file.geojson my_file.shp
````
## Convert your GeoJSON File to Mapbox Vector Tiles
@joshuapowell
joshuapowell / gist:c637a21caf46371ac42b
Created December 4, 2014 16:06
Selecting Appropriate Colors for a Choropleth

Effectively selecting colors for your choropleth map can be intimidating. Thankfully there are a couple of resources that can help us out.

The first is the ColorBrewer website which allows you to tinker with a preset or custom color pallette over a live map.

The second is a preconstructed D3 Map from the mbostock library that contains pre-defined colors, constructed using ColorBrewer.

http://mbostock.github.io/d3/talk/20111018/choropleth.html

@joshuapowell
joshuapowell / gist:e209a4dac5c8187ea8ce
Last active March 11, 2023 18:37
Setup Postgres.app to use PostGIS on OS X

Download and Install Postgres.app

Before we can setup PostGIS we need to have a local version of Postgresql installed and running. The most effecient way to do this is to download and install Postgres.app.

Spatially Enable your Postgres Database

Once Postgres.app is installed in your computers /Applications directory. Open the Terminal and enter the following two commands

psql -d DATABASE_NAME -f /Applications/Postgres.app/Contents/Versions/9.3/share/postgresql/contrib/postgis-2.1/postgis.sql

Virtualenv's bin/activate is Doing It Wrong

I'm a Python programmer and frequently work with the excellent [virtualenv][] tool by Ian Bicking.

Virtualenv is a great tool on the whole but there is one glaring problem: the activate script that virtualenv provides as a convenience to enable its functionality requires you to source it with your shell to invoke it. The activate script sets some environment variables in your current environment and defines for you a deactivate shell function which will (attempt to) help you to undo those changes later.

This pattern is abhorrently wrong and un-unix-y. activate should instead do what ssh-agent does, and launch a sub-shell or sub-command with a modified environment.

Problems