Re: select 1st column element based on criteria in 2nd column in mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg124168] Re: select 1st column element based on criteria in 2nd column in mathematica
- From: "Nasser M. Abbasi" <nma at 12000.org>
- Date: Wed, 11 Jan 2012 06:01:45 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
On 1/11/2012 3:18 AM, Hani wrote:
> hello, I have a question.
>
> Suppose I have a table with two columns like this:
>
> 1 3
> 2 4
> 3 6
> 4 1
> 5 3
> 6 2
> 7 5
> 8 2
>
> I want to select elements of the 1st column which its corresponding 2nd
> column elements are bigger than 3. so, the result should be {2,3,7}. How to
> implement that in mathematica? Thanx a lot
>
one way:
------------------------
mat = {{1, 3}, {2, 4}, {3, 6}, {4, 1}, {5, 3}, {6, 2}, {7, 5}, {8, 2}};
r = Select[mat, #[[2]] > 3 &];
r[[All, 1]]
-----------------
another
----------------------------
mat = {{1, 3}, {2, 4}, {3, 6}, {4, 1}, {5, 3}, {6, 2}, {7, 5}, {8, 2}};
loc = Position[mat, {x_, y_} /; y > 3]
r = Extract[mat, loc];
r[[All, 1]]
----------------------------------------
I am sure there are many more ways.
--Nasser