dwurf

# Instructions to pre-render OSM tiles:

# Start with a clean Ubuntu Trusty 14.04 host

# Need postgis, importer and tools
sudo apt-get install postgresql-9.3 postgis osm2pgsql gdal-bin npm git curl xmlstarlet python-mapnik unzip
# Fonts
sudo apt-get install ttf-dejavu fonts-droid ttf-unifont fonts-sipa-arundina fonts-sil-padauk fonts-khmeros \
ttf-indic-fonts-core ttf-tamil-fonts ttf-kannada-fonts
# nginx -- for leaflet UI

dwurf

Backup of SQL Fiddle code for this StackOverflow answer: http://stackoverflow.com/a/10395492/1349518

dwurf

Mutability of python data types

Most data types in python are immutable, including integers

a = 2
b = a # a and b refer to the same memory location, storing the value 2
b = 5 # b now points to a new memory location, storing the value 5

print a, b 

result: 2 5

dwurf

Branching with git for safe merging

Version Control is a critical tool in any software development project. Despite this, many of us suffer from a crippling fear of one terrifying event: The Dreaded Merge Conflict. Here I'll show you a risk-free way of merging with an easy way to back out if things go belly up.

The scenario

You've been working for hours on a bug fix. Your changes were due an hour ago and you've just finished your unit tests. It's time to upload your changes...

c:\dev>git status
# On branch master

Changes not staged for commit:

dwurf

#!/bin/bash

# Script to leech videos from lca2013
# Will not re-download stuff you already have
# 
# Requires curl, sed and grep
#
# Yes, this parses HTML with regex. Deal with it.
#
# Known bugs:

dwurf

create table bbc (
    region varchar(50) not null,
    name varchar(50) not null primary key,
    population integer
);
 
insert into bbc values ('Oceania', 'Australia', 20);
insert into bbc values ('Oceania', 'New Zealand', 4);
insert into bbc values ('Oceania', 'Solomon Islands', NULL);
insert into bbc values ('Asia', 'Japan', 50);

dwurf

-- Search all varchar columns in an entire database for a specific value
-- DANGER: do not use on large databases. 10k rows **should** be fine, larger than that requires caution.

-- Run this script in a temp database. It needs access to the target database and information_schema to run.
-- Results will go into a temporary table called rset. Everything will be cleaned up once you disconnect.

-- BEGIN SCRIPT --

-- Variables. Modify these, the rest of the script will do the work for you.

dwurf

<?php
        $connstring = "host=localhost dbname=test user=dwurf password=<secret>";
        $conn = pg_connect($connstring);

        $search = ($_GET['term']);
        if (!$conn) { die('Could not connect: ' . pg_last_error ());}
        else
        {

            $sql = "SELECT name FROM users_table WHERE name ILIKE '%$search%' ORDER BY name ASC";