Re: Problem with Position

*To*: mathgroup at smc.vnet.net*Subject*: [mg119650] Re: Problem with Position*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 16 Jun 2011 04:00:21 -0400 (EDT)*Reply-to*: hanlonr at cox.net

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

**Follow-Ups**:**Re: Problem with Position***From:*Dominic Wörner <dominic.woerner@mpi-hd.mpg.de>