FluxTrap: November 2008

Well, it's taking longer than I expected for the parts for my most recent project to come in. I'm waiting for some wireless pigtails (U.FL to RP-SMA) so that my EEE PC has an external antenna (an easy hack, but one I haven't seen any documentation online for).

In the meantime, here's an old video I made a while ago playing with non-Newtonian fluids. This is really easy to make (just saturate water with corn starch) and very fun! Non-Newtonian fluids are fluids whose viscosity is dependant on the applied strain. So, the strain from the speaker constantly hitting the fluid causes it to become much more viscous to the point of appearing solid. This causes all sorts of fun! In this video I played a 100hz sin wave through the speaker. I did this later as a demonstration at the Dragon Academy and I have to say it was a great success, I recommend it for any teachers or demonstrators. Hope everyone enjoys!

OBAMA WON! Truly a day to remember. So, in the spirit of science funding not being slashed to death I am going to release one of my first python scripts that downloads all images off of the NASA Astronomy Picture of the Day (apod).

I tried keeping the code commented so that it could also serve as a good learning tool. One thing I'd like to include is some way of saving the description of the image. This could be done by saving it into a text file with the same filename as the image, but I suspect there is a better way (using ImageMagick to embed the information?). If you have an idea or preference, post a comment! So, here it goes:


#!/bin/env python
#
# Copyright 2008 Michael Gorelick 
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see:
# http://www.gnu.org/licenses/gpl.html.

import re, urllib, sys, os

### Check/Do Help
help = """NASA Image Getter - Michael G. (GPL 2008)
./%s [-h] [imagepath]
imagepath  - path to save images
-h, --help - this help"""%sys.argv[0]

if "-h" in sys.argv or "--help" in sys.argv:
exit(help)
elif len(sys.argv) == 1:
print "Not enough program arguments"
exit(help)

### CONFIG
allowedChars = '[-a-zA-Z0-9*:\'.,&!?\(\)//\n"+;_ ]'
allowedFiles = '[jpg|jpeg|png|gif|mov|avi|mpeg|mpg]'
url = "http://antwrp.gsfc.nasa.gov/apod/archivepix.html"
pbarwidth = 80
try:
imagePath = sys.argv[1]
os.makedirs(imagePath)
except Exception, e:
#errno == 17 means the directory already exists.
if e.errno != 17:
 exit(e)
print "Saving images to %s"%imagePath

##############################################
## This section looks for links to image pages
print "Searching for image pages in", url
html = urllib.urlopen(url).read()
pagePattern = re.compile('([0-9]{6}).html">(' + allowedChars + '*)')
pages = pagePattern.findall(html)
totalpages = len(pages)
print "Found", totalpages, "image pages."

#############################################
## Now we go to the pages and extract a list
##  of images and download
try:
alreadyHave = open(imagePath + "/tracker.log").readlines()
except IOError, e:
alreadyHave = ""
totalhave = len(alreadyHave)
try:
tracker = open(imagePath + "/tracker.log", 'a+')
except IOError, e:
exit(e)

base = url[0:url.rfind('/')]
imagePattern = re.compile('<a href="image/(' + allowedChars + '*.' + \
allowedFiles + ')"', re.IGNORECASE)
sanitizePattern = re.compile('[//\n\r\t]')
imageGet = urllib.URLopener()

for i, page in enumerate(pages):
try:
 if page[0]+"\n" not in alreadyHave:
   #Extract information from image page
   title = sanitizePattern.sub("", page[1])
   currentpage = base + "/ap" + page[0] + ".html"
   print "Getting " + title
   content = urllib.urlopen(currentpage).read()
   image = imagePattern.findall(content)

   #Parse data
   filename = imagePath + "/" + (title + \
     image[0][image[0].rfind('.'):]).replace(" ","_")
   print "\tFilename: " + filename
   url = base + "/image/" + image[0]
   print "\tURL: " + url

   print "\n[" + "="*(pbarwidth*(i-totalhave)/(totalpages-totalhave)) \
     +"@"+"="*(pbarwidth*(i-totalpages)/(totalhave-totalpages)-1)+"]",
   sys.stdout.flush()

   #Download
   imageGet.retrieve(url, filename)
   tracker.write(page[0] + "\n")

   print "\r" + " "*(pbarwidth+2),"\r",
   sys.stdout.flush()
except IndexError, e:
 print "\tImage not found\n"
except IOError, e:
 print "\t404 Error\n"

tracker.close()
print "Done"