Opinion: iPhone vs Android

A friend of mine is finally joining the smartphone using masses and asked to the general Facebook public what type they should get, iPhone or Android (or other).  Here's what I posted in response.

I'm an Android user and will upgrade to another Android when the time comes. I have plenty of iPhone toting friends, and yes, the iPhone is a decent piece of hardware. It is an mobile "experience" that is carefully constructed and controlled by one company - Apple. Therein lies why I won't get an iPhone.

Apple has a knack for keeping people locked to their products. Get an iPhone and you have to get apps that are in the Apple App store, get music/books from Apple's iTunes Store. The iPhone 5 uses a proprietary, and expensive, charging/data sync cable that only Apple sells (and is currently not licensing to third parties). Upgrading iOS has the tendency to remove apps made by companies Apple doesn't like (e.g. Google, as is the case with iOS 6 replacing Google Maps with the poorly excuted Apple Maps). I just don't like that sort of micromanaging - especially by a company who's only after my money.

I won't say that Google/Android is better for everyone. I just know it's better for how I want to use my phone. I like how flexible and customizable it is. I like that it can be useable from a free upgrade phone to a premium one that would cost me $300.

Ultimately, by the numbers iPhones and (premium) Android phones are equivalent. On both you can check your email, post on Facebook, check the weather/traffic, take photos, and occasionally make a phone call. I really depends on who bothers you less as they look over your shoulder - Apple or Google.

Making Color Ramps in Matlab

When visualizing an array of data in a heatmap, a good color map makes a world of difference.

Thanks to my work in 'omics (i.e. transcriptomics - microarrays and RNASeq) I've looked at a lot of heatmaps over the past couple of years, and generated quite a few to boot.  Back in my Matlab heavy grad school days, I was generally happy with the default 'jet' color scheme (which given it's double rainbow-eseque aesthetics would make some individuals on this planet overly emotional).  Suffice it to say, I was a bit wary of straying far from the available maps (the others I used semi-regularly were "bone", "gray", and "hot").

Today I needed to create a nice color ramp in a GUI tool I've developed in Matlab for a dataset that spanned [-Inf, Inf].  Ideally, it should have three color stops:

• a "cool" color for extreme negative values
• a neutral color for 0
• a "hot" color for extreme positive values

The most "viewable" ramp of this sort (e.g. one that the color non-blinds and color blinds can equally enjoy) would be:

• blue
• black
• yellow

If I were generating this ramp in R it would be quite trivial with the colorRampPalette() function:

bky.ramp = colorRampPalette(c('blue', 'black', 'yellow'))

The above line would create a function bky.ramp() that you could use to specify a ramping palette of arbitrary length for a heatmap() (or any other plotting function):

heatmap(X, col=bky.ramp(256))

Doing this in Matlab is similar, but a tad more obscure.  If you look at the help for the colormap() function it says:

A colormap is an m-by-3 matrix of real numbers between 0.0 and 1.0. Each row is an RGB vector that defines one color. The kth row of the colormap defines the kth color, where map(k,:) = [r(k) g(k) b(k)]) specifies the intensity of red, green, and blue.
colormap(map) sets the colormap to the matrix map. If any values in map are outside the interval [0 1], you receive the error Colormap must have values in [0,1].

 I know that the colors I need are:

• blue = [0 0 1]
• black = [0 0 0]
• yellow = [1 1 0]

but how do I ramp between them?  Well for that you need interp1():

 interp1 1-D interpolation (table lookup)
    YI = interp1(X,Y,XI) interpolates to find YI, the values of the
    underlying function Y at the points in the array XI. X must be a
    vector of length N.
    If Y is a vector, then it must also have length N, and YI is the
    same size as XI.  If Y is an array of size [N,D1,D2,...,Dk], then
    the interpolation is performed for each D1-by-D2-by-...-Dk value
    in Y(i,:,:,...,:).
    If XI is a vector of length M, then YI has size [M,D1,D2,...,Dk].
    If XI is an array of size [M1,M2,...,Mj], then YI is of size
    [M1,M2,...,Mj,D1,D2,...,Dk].

In its simplest invocation, it does linear interpolation between supplied points in Y over points XI. How is this used to create a BKY color ramp with 256 levels?  Like so:

bkyramp = interp1([blue; black; yellow], linspace(1,3,256));

If you're the type that likes to encapsulate things in reusable functions (which I am), you end up with something like this: