Omer Khan's Blog

Amazing Planet Earth

omerkhan — Fri, 11 May 2012 19:29:03 +0000

This is an amazing time-lapsed video of the planet Earth taken from Elektro-L, a Russian satellite. Checkout Gizmodo for more details.

Lions, Tigers and Neighbor’s WiFi!

omerkhan — Tue, 10 Apr 2012 03:19:29 +0000

These days you find wi-fi networks every where. This is good. And it’s bad. It’s great having the convenience of wi-fi at coffee shops, restaurants, hotels etc. But it’s a pain when all your neighbors have wi-fi networks that keep interfering with each other.

I recently discovered a handy free utility for the Mac called iStumbler. It lists visible wireless networks in your area and provides lots of useful information such protocol, signal strength, frequency, MAC address etc. But probably the most useful information (if you like me, are having problems with wi-fi network interfering with each other) is the channel that each wi-fi network is using. It’s amazing how many of my neighbor’s routers are using the same channel (which is probably the default setting they came with). I read somewhere that two wireless networks using the same channel share the bandwidth, which halves each others bandwidth. I’m not sure if that’s true, but I’ve got 4 neighbors using the same channel, so their Internet connections must be really slow and certainly not anywhere close to what their probably paying for with Comcast.

Anyway, I just found a free channel that wasn’t being used by anyone, restarted my router and I’m now getting double the download speed (around 10Mbs). Not bad for an old G router.

Steve Blank on the Lean Startup

omerkhan — Tue, 13 Mar 2012 04:28:48 +0000

Here’s Steve Blank’s presentation at SXSW on the theme of lean startups – based on his new book “The Startup Owner’s Manual” (I haven’t read it yet).

The Startup Owners Manual SXSW

View more presentations from Steve Blank

Python for iOS App

omerkhan — Tue, 28 Feb 2012 05:23:16 +0000

I just discovered a new app for my iPhone and iPad — Python for iOS. It supports Python 2.7.2 environment and provides some neat functionality. I can’t see anyone trying to do any serious development with this app, but it’s handy having access to interactive interpreter and being able to run/test scripts.

Amazon – Free 2-Day Shipping Or Would You Like To Pay for It?

omerkhan — Sun, 12 Feb 2012 04:10:07 +0000

I’m a big fan of Amazon.com. I do more than 90% of my shopping online. And I do more than 90% of my online shopping at Amazon.com. I pay $79/year for Prime membership and one of the benefits that I enjoy is free 2 day shipping on many items. I know the folks at Amazon obsess about the customer and how to continuously improve the customer experience. I don’t think there’s any company that provides a better online customer experience. But even Amazon isn’t perfect and it’s moments like this that I’m reminded of that:

Python: Functions with Optional & Named Arguments

omerkhan — Wed, 23 Nov 2011 19:00:24 +0000

Python allows functions to have default values for arguments. These are used when the function is called without the argument. But where it gets really interesting is when you realize that in Python it’s also possible to name the arguments and call them in any order, which can be very useful.

def shirt(styleID, size='Medium', color='White'):
...

For example, in the ‘shirt’ function above, style is a required argument (since it has no default value) but the other two arguments i.e. size and color are optional (since they do have default values assigned).

There are several ways to call this function:

>>> shirt(1)

styleID gets a value of 1 and size and color are assigned their default values.

>>> shirt(1, "Large")

styleID gets a value of 1 and size gets a value of “Large”, while color gets the default value.

>>> shirt(1, color="Black")

styleID gets a value of 1 and color gets a value of “Black”, while size gets the default value.

>>> shirt(size="Small", styleID=2)

size gets a value of “Small” and styleID gets a value of 2, while color gets the default value.

9 Things to Know About Amazon (Infographic)

omerkhan — Mon, 21 Nov 2011 18:48:26 +0000

This is a great infographic about Amazon produced by FrugalDad:

Source: Frugaldad.com

How To Reverse A String in Python

omerkhan — Wed, 16 Nov 2011 01:56:19 +0000

Unlike other languages such as Ruby, there is no built-in method to reverse a string in Python. Here are two possible ways to accomplish that:

1) The 'Long' Way

This approach uses a for-loop with the join method to reverse a string:

def rev(s):
return ''.join([s[i] for i in range(len(s)-1,-1,-1)])

>>> print rev("abcde")
edcba

2) The Simpler Way

This approach uses Python's 'slice notation' to accomplish the same result:

def rev(s):
return s[::-1]

>>> print rev("abcde")
edcba

I think I read somewhere that #1 (for-loop) is faster, but I do love the simplicity of slicing. It looks a little strange at first, if you're not used to Python. But it really is pretty easy to use once you get the hang of it.

Learn Python the Hard Way

omerkhan — Mon, 14 Nov 2011 10:00:32 +0000

Over the last two years, I've spent considerable time learning several programming languages (PHP, C# and Ruby). I started developing web applications with PHP, moved onto ASP.NET MVC using C# and then decided to experiment with Ruby on Rails. I really loved the simplicity of Ruby and the 'magic' of Rails, but there was something about the Ruby language that just didn't grok with me — I still can't exactly put my finger on it.

A couple of months ago, I read Dharmesh Shah's post 'Why PHP is Fun and Easy But Python is Marriage Material'. He made a compelling case for using Python and so a few weeks later I decided to take a closer look at Python myself. As sad as it sounds, I've finally found a programming language that I'm really excited about. It's simple and easy to get started with Python but it's also an extremely powerful language. And after I got over some of the initial 'weirdness' of Python e.g. using tabs for code-blocks, it really started to grow on me.

If you're interested, a great place to start learning Python is Zed Shaw's "Learn Python the Hard Way". The online version of the book is available for free and there's also an online class with screencasts at Udemy.com. The course is really designed for people with little or no programming experience. I consider myself to be a novice, but after a few years of programming in other languages, I realized that I actually know more than I thought I did. It was actually a very easy course for me, which I got through relatively quickly. But it was a great way to learn the fundamentals of Python. It might be too basic for a lot of people, but I still think it's worth taking a quick look at.

At the moment, I'm going through Mark Pilgrim's "Dive Into Python" book — which so far has been EXCELLENT. This is a book for experienced programmers and you will find a ton of useful information here. This book is available for free (published under the GNU Free Documentation License) and can be downloaded in a number of formats and languages. Along with this, I'm also reading Ayman Hourieh's 'Django 1.0 Website Development' book (Django is an excellent web framework for Python). I guess you could call it "Python on Django" but that doesn't quite roll off the tongue as "Ruby on Rails" does.

Introduction to Django

omerkhan — Sun, 23 Oct 2011 05:43:05 +0000

Here's a great introduction to Django from PyCon 2010.