Re: Re: Null entry in a Graphics list?

*To*: mathgroup at smc.vnet.net*Subject*: [mg51885] Re: [mg51856] Re: [mg51795] Null entry in a Graphics list?*From*: "Tom Aldenberg" <Tom.Aldenberg at rivm.nl>*Date*: Thu, 4 Nov 2004 01:49:51 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hi, What I do is wrap every Graphics[ ] thing into list braces: g1={Graphics [ ]}, g2 = {Graphics[ ]}, etc The empty Graphics is then the empty list: g3 = {}. Combining graphics is easy through g123=Join[g1,g2,g3], which gives {-Graphics-,-Graphics-} Show[g123] accepts a list of -Graphics-. Tom Aldenberg Subject: [mg51885] [mg51856] Re: [mg51795] Null entry in a Graphics list? Hi, Graphics[Line[{{0, 0}, {0, 0}}]] should serve as an adequate "Null" graphic. e.g. << Graphics`Graphics` << Graphics`Colors` g1 = Graphics[{Red, Line[{{0, 1}, {1, 0}}]}]; g2 = Graphics[{Blue, Line[{{-1, 0}, {0, 1}}]}]; g3[x_] := If[x < 1, Graphics[{Gold, Circle[{0, 0}, x]}], Graphics[{Green, Line[{{0, 0}, {0, 0}}]}]]; Show[g1, g2, g3[1.3]] Yas On Tue, 2 Nov 2004, AES/newspost wrote: > Is there a "Null" or a "None" for Graphics? > > If I want to accomplish something like > > g1 = Graphics[---]; > g2 = Graphics[---] > g3 = If[test, Graphics[---], NoGraphics ]; > > Show[g1, g2, g3 ]; > > is there something I can put in for "NoGraphics" (other than an > offscreen Point or a zero-size Point or . . . ) that will be acceptable > in subsequent graphics commands >