Geomapping: what a wonderful world!

Suppose you have a set of lat/lon points, where do you find out their elevation?
Simple, let say you have the following coordinates (a cross in concrete on the top of the hill in front of my parents' place):
45.469678, 10.970527 (I got these from 'Get Directions from here' in google maps)
Then call a USGS' web service from the URL below.
It says
getElevation
for Latitude 45.46 --> Y_Value=45.469678
for Longitude 10.97 --> X_Value=10.970527
return result in meters --> Elevation_Units=METERS
use the best survey available --> Source_Layer=-1
not other additional info --> Elevation_Only=true

http://gisdata.usgs.gov/xmlwebservices2/elevation_service.asmx/getElevation?Y_Value=45.469678&X_Value=10.970527&Elevation_Units=METERS&Source_Layer=-1&Elevation_Only=true

Why would you want elevations?

To plot an elevation chart of a bike or hiking tour.

Amazing what you can find around...

(This was inspired by http://econym.org.uk/gmap/altitude.htm)

PyCalCal is out!

I finally set to put PyCalCal out in the open.
I will need to finalize and perfect it but that is a good starting point.
I also added a demo web app using it.

My idea is for PyCalCal to be used as a Python library and as such use it to provide calendrica calculations as web services.
Stay tuned if you are interested.

Giants' Shoulders in music

A nice song about a great Giant, Galileo, by the Chromatics.
Read text and listen to music, here

Scons and noweb

I was curious to see how I could integrate noweb and Scons.

You can download my little Sconstruct for this, Sconstruct.example. It defines two builders. NoWeave is used to produce TeX or LaTeX documents, while NoTangle extracts the non-document artefacts, i.e. programs, config files, scripts ... It also includes productions for generating a sample program about Ackermann function:


ackdoc = env.NoWeave('ack.tex', 'ack.nw')
ackcode = env.NoTangle('ack.py', 'ack.nw')
acktest = env.NoTangle('ackTest.py', 'ack.nw')


The noweb source is ack.nw and the companion BibTeX file is ack.bib

It contains the doc chunks describing the function, the source code chunck for the relevant Python code and the code chunk for the unit test

You can try it out executing

$ scons -f Sconstruct.example

You will get the following artefacts, ack.py, ack.tex, ackTest.py and ack.pdf

Remember to run BibTeX first...

LaTeX, Python and Literate Programming

In my spare time (a couple of hours per weekend...!) I am implementing calcal, a Python version of calendrica-3.0.cl, the Common Lisp implementation of the calendars from N. Dershowitz, E. M. Reingold Calendrical Calculations, 3rd Edition. (In case you are interested you can find a preview in my google page.)
At some point I decided to go Literate [Programming] using noweb. This is an experiment in the experiment but so far it has been a good choice because I can define all I need in the same place and generate documentation, source code (Python, shell scripts ...) from the same source.
I also found something interesting (on a now disappeared blog ttp://usefreetools.blogspot.com): executing Python from within LaTex! I could use it to avoid to hardcode results in my doc and just calculate them on the fly...
The same blog was showing how to build LaTeX docs using SCons: I will defenitly use it; my Makefile isn't that great nor easy to mantain.

My Giants

I am probably too selective, anyway my models for computer science/software engineering (one of them would disagree on both definitions) are just two: Donald E. Knuth and Alan Kay.
The first one continues to surprise me with the depth, clarity and joy of his works: from TeX (well, I use LaTex but it does not exist without TeX) to The Art of Computer Programming to Literate Programming.
About the latter, I was one of the blessed to be present to his Turing Award Lecture: he shocked me to the point I had two sleepless nights so angry I was about having wasted so much time in useless (computer) matters! After that I have been studying and using a lot of what he wrote and presented from Squeak to Croquet to the Burroughs B5000 and stack computers to his recent line of exploration and the proposal to NSF about reinventing programming (PDF).