Re: Something very simple.....

*To*: mathgroup at smc.vnet.net*Subject*: [mg87116] Re: Something very simple.....*From*: dh <dh at metrohm.ch>*Date*: Tue, 1 Apr 2008 05:18:47 -0500 (EST)*References*: <fssr6s$biu$1@smc.vnet.net>

Hi Steve, 1) you must use Map together with Apply: Map[Sphere@@#&,sphlst] 2) here we the complement of the indices and then use Part: lsta[[ Complement[Range[Length[lsta]],lstb]] ] hope this helps, Daniel Steve Gray wrote: > 1. I have a list of sphere centers and radii like this: > > sphlst={{{ 5.11, 0.76, -0.32}, 100.39}, > {{ 7.18, -1.86, -8.19}, 98.02}, > {{26.71, -9.30, -6.85}, 111.27}, > {{ 0, 0, 0}, 100.00}, > {{ 8.65, 4.28, -3.81}, 103.87}}. > > If I do Map[Sphere,sphlst] I get too many braces, like this: > > {Sphere[{{ 5.11, 0.76, -0.32}, 100.39}], > Sphere[{{ 7.18, -1.86, -8.19}, 98.02}], > Sphere[{{26.71, -9.30, -6.85}, 111.27}], > Sphere[{{ 0, 0, 0}, 100.00}], > Sphere[{{ 8.65, 4.28, -3.81}, 103.87}]} > > and Sphere needs for example Sphere[{1.11, 2.22, 3.33},4.5]. > What simple thing am I missing to remove the extra braces? > (I know I can use Table but isn't there a "one-step" method?) > Flatten doesn't seem to be useful here, or I'm using it wrong. > > 2. I have two lists, lsta={a,b,c,d,e,f} and lstb={1,3,4}. > I want the elements of lsta that do NOT correspond to elements > of lstb, in this case everything from lsta except elements > 1,3, and 4: result={b,e,f}. > (lstb won't have entries larger than Length[lsta]). > > Thanks for any tips. > > Steve Gray >