Plot2Kill 0.02

[dsimcha]

== Quote from BLS (windevguy at hotmail.de)'s article
> On 18/07/2010 22:36, dsimcha wrote:
> > heat maps
> Sorry for my ignorance,
> What are heat maps good for ?
> Since I am more biz software guy, here my question.
> Let's say I have this relation
>  >A Project can have several Cost Centers.
>  >A Cost Center can have several cost items.
> I our sample . Project -P- has  say, 10 cost centers.
> Cost Center no 1 takes already 60 percent.
> The other cost centers (2-10) just take between 10 (blue) and 20 (green)
> percent.
> -- So I want to color cost center no 1 related items in red.. . and the
> max percentage item in cost center no 2 dark red.
> CC No 1 = {5,20,20,15}
> Is this what a heat map is made for ?
> and sorry ,  best example I am able to give atm..
> bjoern

You've pretty much got it.  Heat maps can be thought of as a possible counterpart
to bar graphs when you want to plot a dependent variable against two independent
variables instead of one.  The "hot" color is used to represent the largest value
of the dependent variable, the "cold" color is used to represent the smallest
value, and the colors are linearly blended for values in between.

There's also the case of a HeatScatter or 2-D histogram for visualizing a joint
probability distribution.  For small samples, scatter plots are usually used for
this.  However, for large samples, the amount of points on the scatter plot
becomes unwieldy, so instead you bin the data on a 2D grid and the color
represents how often joint realizations with a given pair of values occur.  For
example, the lower right figure in my demo is a HeatScatter where the Y-axis is
distributed Normal(1, 1) and the X-axis is distributed Normal(-2, 1) + Y_i.