S Anand

Hosting options

June 1, 2013 / How I do things / 5 Comments

I’ve been trying out a number of options for hosting recently, and have settled on Amazon spot instances.

Here were my options:

  • Application hosting, like Google AppEngine. I used this a lot until 2 years ago. Then they changed their pricing, and I realised what “lock-in” means. I can’t just take that code and move it to another server. Besides, I’m a bit wary of Google pulling the plug. Heroku? Same problem. I just want to take the code elsewhere and run it.
  • Shared hosting, like Hostgator. This blog is run on Hostgator and I’m extremely happy with them. But the trouble is, with shared hosting, I don’t get to run long-running processes on any ports I like.
  • Run you own servers. The problem here is quite simple: power cuts in India.
  • Dedicated hosting, like Amazon EC2, Azure, GCE, etc. This remains as pretty much the main hosting option

I’m a price optimisation freak. So I ran the numbers for a year’s worth of usage. I was looking at the CPU cost of a large machine with 7-8GB RAM. Bandwidth and storage are negligible. The cost per hour worked out to:

  • Amazon: $0.32 / hr in Singapore, $0.24 in Virginia
  • Google: $0.29 / hr in Europe
  • Microsoft: $0.32 / hr in US

The price is not all that different, but I need low latency, so Singapore it what it’ll have to be.

EC2 location Latency (ms)
Singapore 139
Oregon, US 334
Japan 517
Ireland 618
Australia 620
California, US 677
Virginia, US 710

Now comes the choice of the right model. At $0.32 per hour, that’s $230 a month.

Amazon offers some ways of getting this down. Instead of on-demand instances, I could go for reserved instances. For a year of usage, that’d get the price down to about $131 a month, nearly halving it. ($739 upfront for a heavy utilisation large reserved instance, with $0.095 * 24 * 365.25 for the year.)

In this case, I know I’ll need the servers for a year. Probably more, but then, I might want to switch later. So this isn’t a bad move. But we can do better. Amazon also offers spot instances. Spot instances might get shut down any time – but in reality, so can on-demand instances. I need to plan for it anyway. I’m not going to host anything that’s so sensitive that if it’s down for a few hours, I’ll have a problem.

But what’s attractive is the pricing. Typically, it’s $0.04 per hour, making it about $29 per month. Even if it shoots up to twice that, at $58, it’s less than a fourth of the on-demand price and less than half the reserved instance price.

I’ve managed to script the entire setup up sequence as shell scripts, and it takes less than an hour to get a new server up and running the software I need. I need to work out a decent backup mechanism. Plus, I could use more reliable storage like like Amazon’s EBS to preserve the data. But on the whole, the pricing is far too attractive and makes the risks worthwhile.

Geocoding in Excel

May 8, 2013 / Coding / 2 Comments

It’s easy to convert addresses into latitudes and longitudes into addresses in Excel. Here’s the Github project with a downloadable Excel file.

This is via Visual Basic code for a GoogleGeocode function that geocodes addresses.

Function GoogleGeocode(address As String) As String
    Dim xDoc As New MSXML2.DOMDocument
    xDoc.async = False
    xDoc.Load ("http://maps.googleapis.com/maps/api/geocode/" + _
        "xml?address=" + address + "&sensor=false")
    If xDoc.parseError.ErrorCode <> 0 Then
        GoogleGeocode = xDoc.parseError.reason
    Else
        xDoc.setProperty "SelectionLanguage", "XPath"
        lat = xDoc.SelectSingleNode("//lat").Text
        lng = xDoc.SelectSingleNode("//lng").Text
        GoogleGeocode = lat & "," & lng
    End If
End Function

Goodbye Google

March 16, 2013 / How I do things / 8 Comments

Google Reader was where I spent most of my browsing time, but now, it’s shutting down.

Time for alternatives, but not just for Reader: for all Google products. I’m not sure when one of these might go down, become paid, or become unusable.

I just uninstalled Google Drive and Google Talk. but I don’t use it much (I use Skype), so no loss. I’ll leave Chrome for the while, but I’m hearing reports that Firefox is improving faster than Chrome is. Or there’s Chromium.

I’m not worried much about search services (including image, video, scholar and books). When needed, I can switch. Scholar might be a bit sad to lose, but I don’t use it much. Google Translate, too, isn’t essential.

Likewise for content. YouTube’s not a problem. There’re enough other video services. Trends are useful, but not critical. Maps might be, so I’ll try and switch to OpenStreetMap. I don’t use News or Picasa much.

I don’t care much for social media anyway, so Blogger, Orkut and Plus can die any time.

Google’s apps are the worrying ones. Mail and Calendar, in particular. I’ll probably migrate away from them last, but the attempt is on. I’ll be documenting the alternatives I find at https://gist.github.com/sanand0/5176161 (safely cloned locally).

Looks like there’s no safe long-term alternative to being able to host your own apps. Pity.

Github page-only repository

December 26, 2012 / Coding / Leave a Comment

Github offers Github Pages that let you host web pages on Github.

You create these by adding a branch to git called gh-pages, and this is often in addition to the default branch master.

I just needed the gh-pages branch. So thanks to YJL, here’s the simplest way to do it.

  1. Create the repositoryon github.
  2. Create your local repository and git commitinto it.
  3. Type git push -u origin master:gh-pages
  4. In .git/config, under the [remote "origin"] section, add push = +refs/heads/master:refs/heads/gh-pages

The magic is the last :gh-pages.

The most popular scientific Python modules

December 11, 2012 / Coding / 2 Comments

I just scraped the scientific packages on pypi. Here are the top 50 by downloads.

Name Description Size Downloads
numpy NumPy: array processing for numbers, strings, records, and objects. 2000000 133076
scipy SciPy: Scientific Library for Python 7000000 33990
pygraphviz Python interface to Graphviz 99000 22828
geopy Python Geocoding Toolbox 32000 18617
googlemaps Easy geocoding, reverse geocoding, driving directions, and local search in Python via Google. 69000 15135
Rtree R-Tree spatial index for Python GIS 495000 14370
nltk Natural Language Toolkit 1000000 12844
Shapely Geometric objects, predicates, and operations 93000 12635
pyutilib.component.doc Documentation for the PyUtilib Component Architecture. 372000 10181
geojson Encoder/decoder for simple GIS features 12000 9407
GDAL GDAL: Geospatial Data Abstraction Library 410000 8957
scikits.audiolab A python module to make noise from numpy arrays 1000000 8856
pupynere NetCDF file reader and writer. 16000 8809
scikits.statsmodels Statistical computations and models for use with SciPy 3000000 8761
munkres munkres algorithm for the Assignment Problem 42000 8409
scikit-learn A set of python modules for machine learning and data mining 2000000 7735
networkx Python package for creating and manipulating graphs and networks 1009000 7652
pyephem Scientific-grade astronomy routines 927000 7644
PyBrain PyBrain is the swiss army knife for neural networking. 255000 7313
scikits.learn A set of python modules for machine learning and data mining 1000000 7088
obspy.seisan SEISAN read support for ObsPy. 3000000 6990
obspy.wav WAV(audio) read and write support for ObsPy. 241000 6985
obspy.seishub SeisHub database client for ObsPy. 237000 6941
obspy.sh Q and ASC (Seismic Handler) read and write support for ObsPy. 285000 6926
crcmod CRC Generator 128000 6714
obspy.fissures DHI/Fissures request client for ObsPy. 1000000 6339
stsci.distutils distutils/packaging-related utilities used by some of STScI’s packages 25000 6215
pyopencl Python wrapper for OpenCL 1000000 6124
Kivy A software library for rapid development of hardware-accelerated multitouch applications. 11000000 5879
speech A clean interface to Windows speech recognition and text-to-speech capabilities. 17000 5809
patsy A Python package for describing statistical models and for building design matrices. 276000 5517
periodictable Extensible periodic table of the elements 775000 5498
pymorphy Morphological analyzer (POS tagger + inflection engine) for Russian and English (+perhaps German) languages. 70000 5174
imposm.parser Fast and easy OpenStreetMap XML/PBF parser. 31000 4940
hcluster A hierarchical clustering package for Scipy. 442000 4761
obspy.core ObsPy – a Python framework for seismological observatories. 487000 4608
Pyevolve A complete python genetic algorithm framework 99000 4509
scikits.ann Approximate Nearest Neighbor library wrapper for Numpy 82000 4368
obspy.imaging Plotting routines for ObsPy. 324000 4356
obspy.xseed Dataless SEED, RESP and XML-SEED read and write support for ObsPy. 2000000 4331
obspy.sac SAC read and write support for ObsPy. 306000 4319
obspy.arclink ArcLink/WebDC client for ObsPy. 247000 4164
obspy.iris IRIS Web service client for ObsPy. 261000 4153
Orange Machine learning and interactive data mining toolbox. 14000000 4099
obspy.neries NERIES Web service client for ObsPy. 239000 4066
pandas Powerful data structures for data analysis, time series,and statistics 2000000 4037
pycuda Python wrapper for Nvidia CUDA 1000000 4030
GeoAlchemy Using SQLAlchemy with Spatial Databases 159000 3881
pyfits Reads FITS images and tables into numpy arrays and manipulates FITS headers 748000 3746
HTSeq A framework to process and analyze data from high-throughput sequencing (HTS) assays 523000 3720
pyopencv PyOpenCV – A Python wrapper for OpenCV 2.x using Boost.Python and NumPy 354000 3660
thredds THREDDS catalog generator. 25000 3622
hachoir-subfile Find subfile in any binary stream 16000 3540
fluid Procedures to study geophysical fluids on Python. 210000 3520
pygeocoder Python interface for Google Geocoding API V3. Can be used to easily geocode, reverse geocode, validate and format addresses. 7000 3514
csc-pysparse A fast sparse matrix library for Python (Commonsense Computing version) 111000 3455
topex A very simple library to interpret and load TOPEX/JASON altimetry data 7000 3378
arrayterator Buffered iterator for big arrays. 7000 3320
python-igraph High performance graph data structures and algorithms 3000000 3260
csvkit A library of utilities for working with CSV, the king of tabular file formats. 29000 3236
PyVISA Python VISA bindings for GPIB, RS232, and USB instruments 237000 3201
Quadtree Quadtree spatial index for Python GIS 40000 3000
ProxyHTTPServer ProxyHTTPServer — from the creator of PyWebRun 3000 2991
mpmath Python library for arbitrary-precision floating-point arithmetic 1000000 2901
bigfloat Arbitrary precision correctly-rounded floating point arithmetic, via MPFR. 126000 2879
SimPy Event discrete, process based simulation for Python. 5000000 2871
Delny Delaunay triangulation 18000 2790
pymc Markov Chain Monte Carlo sampling toolkit. 1000000 2727
PyBUFR Pure Python library to encode and decode BUFR. 10000 2676
collective.geo.bundle Plone Maps (collective.geo) 11000 2676
dap DAP (Data Access Protocol) client and server for Python. 125000 2598
rq RQ is a simple, lightweight, library for creating background jobs, and processing them. 29000 2590
pyinterval Interval arithmetic in Python 397000 2558
StarCluster StarCluster is a utility for creating and managing computing clusters hosted on Amazon’s Elastic Compute Cloud (EC2). 2000000 2521
fisher Fast Fisher’s Exact Test 43000 2503
mathdom MathDOM – Content MathML in Python 169000 2482
img2txt superseded by asciiporn, http://pypi.python.org/pypi/asciiporn 443000 2436
DendroPy A Python library for phylogenetics and phylogenetic computing: reading, writing, simulation, processing and manipulation of phylogenetic trees (phylogenies) and characters. 6000000 2349
geolocator geolocator library: locate places and calculate distances between them 26000 2342
MyProxyClient MyProxy Client 67000 2325
PyUblas Seamless Numpy-UBlas interoperability 51000 2252
oroboros Astrology software 1000000 2228
textmining Python Text Mining Utilities 1000000 2198
scikits.talkbox Talkbox, a set of python modules for speech/signal processing 147000 2188
asciitable Extensible ASCII table reader and writer 312000 2160
scikits.samplerate A python module for high quality audio resampling 368000 2151
tabular Tabular data container and associated convenience routines in Python 52000 2114
pywcs Python wrappers to WCSLIB 2000000 2081
DeliciousAPI Unofficial Python API for retrieving data from Delicious.com 19000 2038
hachoir-regex Manipulation of regular expressions (regex) 31000 2031
Kamaelia Kamaelia – Multimedia & Server Development Kit 2000000 2007
seawater Seawater Libray for Python 2000000 1985
descartes Use geometric objects as matplotlib paths and patches 3000 1983
vectorformats geographic data serialization/deserialization library 10000 1949
PyMT A framework for making accelerated multitouch UI 18000000 1945
times Times is a small, minimalistic, Python library for dealing with time conversions between universal time and arbitrary timezones. 4000 1929
CocoPy Python implementation of the famous CoCo/R LL(k) compiler generator. 302000 1913
django-shapes Upload and export shapefiles using GeoDjango. 9000 1901
sympy Computer algebra system (CAS) in Python 5000000 1842
pyfasta fast, memory-efficient, pythonic (and command-line) access to fasta sequence files 14000 1836

Streaming audio to iOS via VLC

October 13, 2012 / How I do things / 1 Comment

You can play a song on your PC and listen to it on your iPhone / iPad – converting your PC into a radio station. As with most things VLC related, it’s tough to figure out but obvious in retrospect.

The first thing to do is set up the MIME type for the streaming. This is a bug that has been fixed, but might not have made it into your version of VLC.

Go to Tools – Preferences.

vlc-pref-1

Click on “All” to see all the settings.

vlc-pref-2

Under Stream output – Access output – HTTP, set Mime to audio/x-mpeg.

vlc-pref-3

At this point, you should restart VLC.

As I mentioned earlier, you might not need to do this if you have new enough a version of VLC that auto-detects the content’s MIME type.

Re-open VLC, and go to the Media – Stream menu.

vlc-stream-1

Click Add and choose the file you want to stream. Then click on Stream.

vlc-stream-2

Click Next.

vlc-stream-3

Select HTTP and click Add.

vlc-stream-4

Select Audio – MP3 and click on Stream.

vlc-stream-5

At this point, the audio is being streamed at port 8080 of your machine. You can change the port and path in the menu above. (To find your local IP address, open the Command Prompt and type ipconfig.)

Open Safari on your iPhone or iPad, and visit http://your-ip-address:8080/

vlc-ipad-streaming

I haven’t figured out the right codec and MIME type to do this for videos yet, but hopefully will figure it out soon.

Magnetix

October 2, 2012 / Interesting experiences / 2 Comments

I wasn’t entirely sure, but now I’m somewhat convinced: Magnetix magnets can form an infinite chain that won’t break due by its own weight.

photo 1 photo 2

(This is not true, however, if you introduce the steel bearing balls between them. That structure collapses pretty quickly if you pull it up like a chain.)

So, this would be a really nice question for What If, IMHO. What if you made a 1 light-year chain of Magnetix? Well, to begin with, we’d need nearly 40 million trillion pieces. That’d cost at least 10 million trillion dollars based on the current prices at Amazon, and would be about 140,000 times the world’s GDP. I’m sure Randall could take this a lot further.

Auto reloading pages

September 30, 2012 / Coding / Leave a Comment

After watching Bret Victor’s Inventing on Principle, I just had to figure out a way of getting live reloading to work. I know about LiveReload, of course, and everything I’ve heard about it is good. But their Windows version is in alpha, and I’m not about to experiment just yet.

This little script does it for me instead:

(function(interval, location) {
  var lastdate = "";
  function updateIfChanged() {
    var req = new XMLHttpRequest();
    req.open('HEAD', location.href, false);
    req.send(null);
    var date = req.getResponseHeader('Last-Modified');
    if (!lastdate) {
      lastdate = date;
    }
    else if (lastdate != date) {
      location.reload();;
    }
  };
  setInterval(updateIfChanged, interval);
})(300, window.location)

 

It checks the current page every 300 milliseconds and reloads it if the Last-Modified header is changed. I usually include it as a minified script:

<script>(function(d,c){var b="";setInterval(function(){var a=new
XMLHttpRequest;a.open("HEAD",c.href,false);a.send(null);
a=a.getResponseHeader("Last-Modified");if(b)b!=a&&
c.reload();else b=a},d)})(300,window.location)</script>

There are no dependencies on any library, like jQuery. However, it requires that the file be on a web server. (It’s easy to fix that, but since I always run a local webserver, I’ll let you solve that problem yourself.)

Windows XP virtual machine

September 18, 2012 / Coding / 2 Comments

Here’s the easiest way to set up a Windows XP virtual machine that I could find.

(This is useful if you want to try out programs without installing it on your main machine; test your code on a new machine; or test your website on IE6 / IE7 / IE8.)

  1. Go to the Virtual PC download site. (I tried VirtualBox and VMWare Player. Virtual PC is better if you’re running Windows on Windows.)
    image
    If you have Windows 7 Starter or Home, select “Don’t need XP Mode and want VPC only? Download Windows Virtual PC without Windows XP Mode.”
    If you have Windows Vista or Windows 7, select “Looking for Virtual PC 2007?”
  2. Download it. (You may have to jump through a few hoops like activation.)
  3. Download Windows XP and run it to extract the files. (It’s a 400MB download.)
  4. Open the “Windows XP.vmc” file – just double-clicking ought to work. At this point, you have a working Windows XP version. (The Administrator password is “Password1”.)
  5. Under Tools – Settings – Networking – Adapter 1, select “Shared Networking (NAT)”
    image

That’s pretty much it. You’ve got a Windows XP machine running inside your other Windows machine.

Update (18 Sep 2012): I noticed something weird. The memory usage of VMWindow and vpc.exe is tiny!

image

Between the two processes, they take up less than 30MB of memory. This is despite the Windows XP Task Manager inside the virtual machine showing me 170MB of usage. I’ve no clue what’s happening, but am beginning to enjoy virtualisation. I’ll start up a few more machines, and perhaps install a database cluster across them.