Re: Online Graphic Output

*To*: mathgroup at smc.vnet.net*Subject*: [mg97860] Re: Online Graphic Output*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Tue, 24 Mar 2009 05:30:05 -0500 (EST)*References*: <gq2f1m$efh$1@smc.vnet.net>

> > Thank You for your advice. But I could not solve my problem. > Therefore I reduced the problem to a simple code example: > > Do[{ x = Random[], y = Random[], p = Point[{x, y}], > Graphics[{PointSize[0.1], p}, GridLines -> Automatic, > Frame -> True, PlotRange -> { {-1, 1}, {-1, 1}}]} , > {n, 1, 5}] > > I would like to receive a single graphic with 5 points plotted. > The statements within the Do loop show nothing, not even a error > message with the Mathematica version 7. > A Do loop does not generate output. If you want to see results you have to explicitly print them using Print[ ]. This works for values and graphics alike. In your case, the loop doesn't generate a single graph with 5 points, but 5 graphs with each a single point. Furthermore, you are using commas to make a compound statement whereas Mathematica requires a semicolon (;) for that purpose. Also, you are probably confusing Do and Table. You would like to have a list of points. A minimal modification of your code that works would then be: Graphics[ Prepend[ Table[ x = Random[]; y = Random[]; Point[{x, y}], {n, 1, 5} ], PointSize[0.1] ], GridLines -> Automatic, Frame -> True, PlotRange -> {{-1, 1}, {-1, 1}} ] However, this is still pretty ugly. It can be written much more elegantly: Graphics[ { PointSize[0.1], Point[RandomReal[{0, 1}, {5, 2}]] }, GridLines -> Automatic, Frame -> True, PlotRange -> {{-1, 1}, {-1, 1}} ] This uses the fact that Point is listable, i.e. can work on a list of points. It also uses the efficient RandomReal that is able to generate multi-dimensional list of random numbers. One final remark: The range of the random points and your choice for PlotRange do not coincide. You should change PlotRange or the RandomReal statement (in RandomReal[{-1, 1}, {5, 2}]) Cheers -- Sjoerd On Mar 21, 12:20 pm, felixheiner <werner.lech... at t-online.de> wrote: > Normally Mathematica uses data sets that are collected before plotting. I= receive a data stream from internet and I would like to display these data= points immediately. A typical application of this kind could be a online c= hart of changing prices. Although I am an experienced user of Mathematica 2= -7 for many years, I do not know, how to program this application type. Cou= ld anybody help out ?