Re: Problem with Position
- To: mathgroup at smc.vnet.net
- Subject: [mg119662] Re: Problem with Position
- From: Dominic Wörner <dominic.woerner at mpi-hd.mpg.de>
- Date: Thu, 16 Jun 2011 06:23:01 -0400 (EDT)
- References: <201106160800.EAA13185@smc.vnet.net>
Thank you Bob. This works perfectly in my case Best, Dominic Am 16.06.2011 um 10:00 schrieb Bob Hanlon: > > Perhaps the numbers have more decimal places than what is displayed = and you > need to round to the precision of the index key. > > choices = {0.123456, 0.654321, 0.785398}; > > data = Table[{ > RandomChoice[choices] + 10^-7*Random[], > RandomReal[], RandomReal[]}, {10}]; > > Flatten@ > Position[N[Round[data[[All, 1]], 10^-6]], > 0.785398] > > {2, 5, 6, 9} > > Flatten@ > Position[N[Round[data[[All, 1]], 10^-6]], #] & /@ > choices > > {{1, 3, 4, 8}, {7, 10}, {2, 5, 6, 9}} > > Alternatively, > > Flatten@ > Position[data[[All, 1]], > _?(Abs[# - 0.785398] < 10^-6 &)] > > {2, 5, 6, 9} > > Table[ > Flatten@Position[data[[All, 1]], > _?(Abs[# - c] < 10^-6 &)], > {c, choices}] > > {{1, 3, 4, 8}, {7, 10}, {2, 5, 6, 9}} > > > Bob Hanlon > > ---- "Dominic W=C3=B6rner" <dominic.woerner at mpi-hd.mpg.de> wrote: > > ============= > Hi, > > I have to import data from a csv file. And I get a structure = data[[rows]] ={first, second,...}. > Now I want to find the rows in which, say the first entry has a = specific values. > By just looking at the data there are for example entries with value = 0.785398. > But when I try Flatten@Position[data[[All,1]],0.785398] or with = ToString[0.785398] I just get {} > > What's the problem here? > > Best, > Dominic > >
- References:
- Re: Problem with Position
- From: Bob Hanlon <hanlonr@cox.net>
- Re: Problem with Position