Simulating the Golden Balls game show
In this eposide of Golden Balls, an inspired event takes place: I retold the event at DIKU APL lunch (nice to have a job where game theory is a valid conversation topic), and we had a conversation about it. At…
Difficulty 2 · Easy
Difficulty level 2 of 5: Easy
How to remove extended attributes from a file edited with TextMate
If you run ‘ll -l’ sometimes a file has ‘@’ permission. This means that the file has extended attributes. TextMate may extended attributes to a file. Consider a fictional Python file called xxx.py edited with TextMate: View extended attributes: $…
Incrementing part of an array in numpy
given a (2D) array a, and a smaller (2D) array b, how can you add the smaller array to the bigger array at some offset in numpy? >>> a = zeros((4,4), dtype=int) >>> a array([[0, 0, 0, 0], [0, 0,…
Quick benchmarking of Python code with timeit
How long does [insert code snippet] take in Python? Find out with the timeit module, in Python since 2.3. Below I time how long it takes to make a list with a 1000 zeros, [0,0,0,…], using different Python code snippets.…
Never forget your password again, version 1
The recommended practice is to have different passwords on different websites. But how do you remember all those passwords without storing them somewhere? The tricks is, you don’t. You remember a single strong password, and use a mechanism to generate…
Python module for processing a file line-by-line
Note: Since writing this post, I’ve learned about the fileinput module, which turns most of the following into a oneliner: import fileinput for line in fileinput.input(): process(line)
A map application that shows different tile schemes
Here is a map application that illustrates very well the different tile schemes used (TMS, QuadTree, Google Maps):
Importing data from a CSV file into a Postgres table
Simple CSV file import You have a CSV file called “data.csv”. It has a header line, and is delimited using “;”. You want to import it into Postgres and a table called “your_table”: Create the database table. Set column-types so…
How to load an ESRI Shapefile into a PostGIS DB
Assuming a shapefile called myshapefile.shp, a table mytable in schema xyz, in a PostGIS enabled database called mydb on localhost. The table is owned by user dbuser who has password “secret”. Using shp2pgsql shp2pgsql myshapefile -I xyz.mytable > statements.sql psql…
Installing pip and virtualenv on Mac
These instructions show how to install pip and virtualevn on a Mac running Snow Leopard 10.6.8 and using Python 2.7. I used this to install Django 1.3.1 (installation instructions included). Installing pip (skip if you have pip installed) First make…