Re: How to get elements satisfying specific condition from a list
- To: mathgroup at smc.vnet.net
- Subject: [mg123401] Re: How to get elements satisfying specific condition from a list
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Mon, 5 Dec 2011 05:17:42 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
a = Range[0, 9]; Select[a, Sqrt[#] > 2 &] {5, 6, 7, 8, 9} b = Table[{x, y}, {x, 1, 6}, {y, 1, 6}]; Select[Flatten[b, 1], First@# + Last@# > 9 &] {{4, 6}, {5, 5}, {5, 6}, {6, 4}, {6, 5}, {6, 6}} For each example, the function doing the work is Select. Its first argument is the list from which to select; its second argument is the pure function prescribing the condition by which to select. In the second example, b is a two-dimensional table, so first you use Flatten[b, 1] to join all its rows one after the other into a single long list of pairs. On 12/4/11 2:51 AM, e-changb wrote: > Hi, please help me if you can.. Let > > B:= Table[{x, y}, {x, 1, 6}, {y, 1, 6}] > > It is clear that B has 36 elements. > > I want to get the list of elements satisfying > 'the first component + second component is bigger than 9' > > so that the answer is > > {{5,5},{5,6},{6,5},{6,6}}. > > In fact, I have no idea for following even simpler problem. : Let A be a set of all natural numbers less than 10. Find every element whose squre root is bigger than 2. (needless to say the answer is {5,6,7,8,9}) > > Can you help me ? > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305