Re: Conditional list indexing

*To*: mathgroup at smc.vnet.net*Subject*: [mg95908] Re: Conditional list indexing*From*: Joerg <schaber at biologie.hu-berlin.de>*Date*: Thu, 29 Jan 2009 05:58:44 -0500 (EST)*References*: <glpgd4$lha$1@smc.vnet.net>

maybe not the nicest way: Flatten[Position[# > 15 & /@ a, True]] best, joerg daniele schrieb: > Hello everybody, > I'd like to know how I can get the indices of the elements in a list > that satisfy a certain condition. Here's an example: suppose I have > the list > > a = Table[Prime[i],{i,10}]; > > that contains {2,3,5,7,11,13,17,19,23,29}. > > If I execute the command > > b = Select[a,#>15&]; > > b will contain {17,19,23,29}. I'd like to find a way to obtain a third > list, say c, that will contain {7,8,9,10}, i.e. the indices of the > elements in list a that are greater than 15. > > Thank you, > Daniele > >