[Gnuplot-info] Multiple individual dotted lines

[Hamish A. <ham...@go...>]

Hi,

I'm trying to create a visual demonstration of how Principle Components 
Analysis works in projecting two-dimensional data into one dimension. 
So I have created some 2D datapoints which lie along a diagonal line, 
with some Gaussian noise thrown in.

Using PCA I can determine the vectors of the principle components. Then 
I want to plot lines for those vectors, which should bisect one another 
on the diagram. First question: I'd like those lines to have arrowheads 
on each end (so that they look like axes). How can I achieve this?

Second question: I can create a second 2D dataset which is the 
projection of the original datapoints onto the principle component, so 
that they all lie on the line of the principle component. I would like 
to draw dotted or dashed lines between each original datapoint and its 
new position. It's not clear to me how I would best achieve this. Can 
anyone give me any advice?

Many thanks,
Hamish