Re: Re: Re: How to combine graphics

*To*: mathgroup at smc.vnet.net*Subject*: [mg107128] Re: [mg107089] Re: [mg107024] Re: [mg107011] How to combine graphics*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Wed, 3 Feb 2010 06:12:13 -0500 (EST)*References*: <201001311253.HAA14187@smc.vnet.net>*Reply-to*: drmajorbob at yahoo.com

I'd forgotten about Draw2D's scoping of directives in sublists. Bobby On Tue, 02 Feb 2010 02:30:03 -0600, Murray Eisenberg <murray at math.umass.edu> wrote: > Bobby, > > As a devoted and experienced user of Presentations, of course I'm well > aware that enlisting Red and Line[points] is unnecessary. > > However, as a matter of my programming style preferences and to avoid > unwanted effects, I make it a practice whenever I can to use the extra > list, as in > > Draw2D[{Draw[Sin[x], {x, -Pi, Pi}], {Red,Line[points]}}, Axes -> True] > > or at the very least to pretty-print my expression in a form such as > > Draw2D[{ > Draw[Sin[x], {x, -Pi, Pi}], > Red, Line[points] > }, Axes -> True] > > so as clarify that the intention is to apply the Red directive to what > follows immediately (on the same line). > > If one avoids the extra braces, then the avoidance of unwanted effects > occurs in something like the following: > > Draw2D[{Draw[Sin[x],{x,-Pi,Pi}],Red,Line[points], > Draw[x^2, {x,-Pi,Pi}]},Axes->True] > > As it stands, the parabola would be drawn in Red, too; that may or may > not be what was really intended. Using the extra list -- > > Draw2D[{Draw[Sin[x],{x,-Pi,Pi}],{Red,Line[points]}, > Draw[x^2, {x,-Pi,Pi}]},Axes->True] > > -- avoids the problem, as of course does the alternative of explicitly > changing color back again: > > Draw2D[{Draw[Sin[x],{x,-Pi,Pi}], > Red,Line[points], > Black, Draw[x^2, {x,-Pi,Pi}]},Axes->True] > > I have no objection to the latter but prefer to use it when I want yet a > third color for the third graphics object. > > Presentations allows those variants all to work, to suit one's fancy, > while still allowing with all its oh-so-useful paradigm of simply > listing the graphics objects and directives one after the other. > > Murray > On 2/1/2010 8:54 PM, DrMajorBob wrote: >> Presentations gives the same graph with even LESS complexity, too: >> >> Draw2D[{Draw[Sin[x], {x, -Pi, Pi}], Red, Line[points]}, Axes -> True] >> >> (No need to put Red and Line in a List together.) >> >> I think David deliberately made Draw2D's argument a List in order to >> emphasize this point, or something like it. Directives and graphics are >> sequentially applied, and Draw2D options apply to the overall drawing. >> >> This works just as we'd expect it to, as well: >> >> Draw2D[{Blue, Draw[Sin[x], {x, -Pi, Pi}], Red, Line[points], >> Draw[Cos[x], {x, -Pi, Pi}]}, Axes -> True] >> >> and so does this: >> >> Draw2D[{Blue, Draw[Sin[x], {x, -Pi, Pi}], Red, Line[points], >> Draw[Cos[x], {x, -Pi, Pi}]}, Axes -> True, AxesStyle -> Purple, >> Background -> LightPink] >> >> Bobby >> >> On Mon, 01 Feb 2010 05:09:40 -0600, Murray Eisenberg >> <murray at math.umass.edu> wrote: >> >>> Trying to do this kind of thing using Mathematica's built-in paradigm >>> for graphics causes trouble for many beginners. >>> >>> Here's one way. (I changed the x-domain because otherwise the random >>> polygon collapses to a small blur.) >>> >>> points = RandomReal[{-1,1},{100,2}]; >>> Show[{ >>> Plot[Sin[x],{x,-Pi,Pi}], >>> Graphics[{Red,Line[points]}] >>> }] >>> >>> The Graphics has to apply only to the {Red,Line[points]}, as the result >>> of the Plot expression is already a Graphics object. >>> >>> You don't need the Axes->True option, as that's the default for Plot. >>> However -- and this really drives folks nuts -- if you reverse the >>> order >>> of the Graphics objects... >>> >>> Show[{Graphics[{Red,Line[points]}], Plot[Sin[x], {x,-Pi,Pi}]}] >>> >>> ... then the axes disappear and you have to insert the Axes->True >>> option >>> within the Graphics[{Red,Line[points]}] expression: >>> >>> Show[{Graphics[{Red, Line[points]}, Axes -> True], >>> Plot[Sin[x], {x, - Pi, Pi}]}] >>> >>> No wonder this sort of thing gives so much trouble! >>> >>> But a much simpler way to do the whole thing is to use the different >>> paradigm that's supplied by David Park's Presentations application: >>> >>> Needs["Presentations`Master`"] >>> >>> points = RandomReal[{-1,1},{100,2}]; >>> >>> Draw2D[{ >>> Draw[Sin[x],{x,-Pi,Pi}], >>> {Red,Line[points]} >>> }, >>> Axes->True] >>> >>> Notice that the Axes->True option is for the entire Draw2D expression; >>> this means you'll get axes without any further ado no matter in what >>> order you list the two objects, Draw[Sin[x]....] and >>> {Red,Line[points]}. >>> >>> I've deliberately pretty-printed both versions in order to emphasize >>> the >>> structure of the overall expression. >>> >>> In the version done with Presentations, notice that all the different >>> objects to be drawn (by the Draw2D) are "at the same level", one after >>> the other, so that there's no need for wrapping the {Red,Line[points] >>> expression with Graphics. >>> >>> With Presentations, moreover, you don't have to explicitly form pairs >>> of >>> reals as coordinates of the points, but may instead form complex >>> numbers >>> directly and plot a "complex line" whose vertices are the corresponding >>> complex points: >>> >>> points = RandomComplex[{-1 - I, 1 + I}, 100]; >>> Draw2D[{Draw[Sin[x],{x,-Pi,Pi}],Red,ComplexLine[pts]},Axes->True] >>> >>> >>> On 1/31/2010 7:53 AM, a boy wrote: >>>> points = RandomReal[{-1, 1}, {100, 2}] >>>> Graphics[{Red, Line[points], Plot[Sin[x], {x, -10 Pi, 10 Pi}]}, >>>> Axes -> True] >>> >> >> > -- DrMajorBob at yahoo.com

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