[NCLUG] GD Charting Tutorials

[R P Herrold]

On Sun, 21 Dec 2008, Dave Treece wrote:

> Curiosity getting the best of me, but can anyone recommend a 
> good book or web site that can explain in somewhat basic 
> terms the process of building charts?

Probably the best source I know of is at:

 	http://gnuplot.sourceforge.net/demo_4.3/

which has both charts, and the rule sets used to make them, 
side by side, so one can see 'how it was done'

This page:
    http://gnuplot.sourceforge.net/demo_4.3/finance.html
shows, step by step, building up layers of financial chart 
detail.  The author is well known in financial circles ( and a 
personal friend and correspondent), and provide access to 
'real data' for analysing mutual funds (and more) with 'sliders' at 
several sites linked off of:
    http://www.fundstrader.com/

gnuplot and GD are quite similar, and as I recall there is a 
perl-GD package to permit building GD objects more easily.

I threw the charts (20 years of November and December daily 
data on CSCO's stock price), in about an hour when asked a 
question recently about its historical price movement each 
October and November:
     http://www.herrold.com/CSCO/

The generative script did minimal 'scaling' to determine the 
high and low, and add a bit of 'leeway' at each end, and them 
put a 'scale' of trading days from the start of Oct, and the 
start of Nov; also the chart axes captioning was done in 
gnuplot.  notice the mix of linear (top) and log (bottom) 
charts for eash set

Using John Bollinger's example, I could have added moving 
averages, and bars, but it was not needed, as 'eyeballing' the 
plots answered the question we had.

-- Russ herrold