RE: [GD-DEVEL] plotting data txt array

Hi Pierre et al,

This is exactly what I do with gd but with GPS data. Using C++, I open a
text file, instantiate a class of moving objects, work out all kinds of max,
min, average and standard deviation for velocity, altitude, gradient, power,
time independent altitude profile etc then use a very crude Newton-Raphson
hack to try and smooth out multipath (ghosting) errors in the GPS reported
height. Finally I calculate each point's closest approach to a series of
waypoints and use gd to give me a simple map (lon / lat) and a series of
pseudo-3D JPEGs showing profile, velocity, gradient and power and known
waypoints.

I can take a 10,000 point log file and 150 member waypoint file and have it
all analysed, averaged, summarised and graphed with an HTML interface in
under 4 seconds. That's C++ and gdLib - not me!

gdLib was the first utility I found that actually did what it should without
me having to modify undocumented parameters or similar gotchas.

For a little while I've been thinking of making a simple tutorial with C++
source to take a user through the basics, because it took me awhile to learn
how to plot to a canvas without wanting to learn matrix manipulation. I
compromise with a graphClass that calculates the rotation and shadow for
each point, then graphs it. It has never failed, apart from the bugs in my
own code.

So give me a path on the server and a few weeks. I'll write an article on
drawing basic graphics, upload some platform-independent source files and
get others to critique it.

Cheers,

Bill



-----Original Message-----
From: Pierre Joye [mailto:[email protected]] 
Sent: Wednesday, 23 January 2008 12:22 PM
To: Patolfo
Cc: [email protected]
Subject: Re: [GD-DEVEL] plotting data txt array

Hi,

On Jan 23, 2008 1:55 AM, Patolfo <[email protected]> wrote:
> good day guys, i am making some work for college now, and well i am
> doing some kind of dft, discrete fourier transform basics, right now i
> am approximating sine waves by means of sampling, and some spicing. The
> problem is i do have the results in a txt file, yes that was the home
> work to work out some algorithm to have this txt data and view it on
> console, but i want to go a step furter, well i have the txt data why
> not plotting it, so far i tried mathgl, but well i could not do it, i
> did some google but not much found, so i come to you, there is some
> place where i can learn view, or copy the way of ploting data using gd
> and pure c code or cpp.

You can use gdChart and write the parser for your text file (or pass
the data directly instead of saving them in this text file):

http://www.fred.net/brv/chart/

Cheers,
-- 
Pierre
http://blog.thepimp.net | http://www.libgd.org

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