This is a good post showing how “perrygeo” uses Cython to speed up a pure Python function. The comments also discuss alternatives and options:
- Using psyco instead of Cython
- Using optimization flags for gcc
- Using xxx instead of math.xxx
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. Notice that you can time snippets directly on the commandline, without writing a script file (.py) or running the Python interpreter interactively.
$ python -m timeit 'import numpy' 'a = numpy.zeros(shape=(1,1000))' 100000 loops, best of 3: 2.38 usec per loop
I tried the Tor browser today, and was amazed at how slow it was. As Tor’s user base has grown, the performance of the Tor network has suﬀered. This document describes
the current understanding of why Tor is slow, and lays out the options for ﬁxing it.
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 other passwords from that.
This is not for securing government secrets, but should work for your twitter account.
There are many ways to do this: http://xkcd.com/936/
In this post I’ll compare the running time of reading uncompressed and compressed files from disc.
I’ll run a test using two files, data.txt (858M) and data.txt.gz (83M), that have the same content.
The well-known command cat, prints the contents of a file. The lesser-known zcat, prints the contents of a GZIP’ed file.
Here is a map application that illustrates very well the different tile schemes used (TMS, QuadTree, Google Maps):
Online documentation for GDAL/OGR Python is sparse. Here I show some recommended ways of learning more about GDAL/OGR in Python.
You can learn about GDAL and OGR from inside the Python interpreter.
Start python interpreter:
Import the modules:
from osgeo import gdal,ogr,osr
Learn about the modules using ‘help’ and ‘dir’ in Python. These built-in functions work for any type of object (module, class, functions etc):
help(ogr) # display help for the ogr module dir(ogr) # what's contained in ogr module? help(ogr.Geometry) # display help for ogr.Geometry class dir(ogr.Geometry) # show contents of an object, like functions on a class
gis.stackexchange.com is a Q&A site about GIS. Many people here know about GDAL and ORG, also about the Python bindings.
Some good questions I’ve found:
Transformation using OGR in Python
Will add more as I find them…
GDAL is not very well documented, and a complete Python API documentation site is not something I’ve found. So here are the best tutorials I’ve found so far for GDAL + Python.