Re: select 1st column element based on criteria in 2nd column in mathematica
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- Subject: [mg124196] Re: select 1st column element based on criteria in 2nd column in mathematica
- From: "Oleksandr Rasputinov" <oleksandr_rasputinov at hmamail.com>
- Date: Thu, 12 Jan 2012 04:21:45 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
Or maybe:
Pick[#1, Thread[#2 > 3]] & @@ Transpose[pairs]
On Wed, 11 Jan 2012 22:25:16 -0000, Murray Eisenberg
<murray at math.umass.edu> wrote:
> You cannot directly select from a "table", as there is no such object in
> Mathematica. You want to select from a list of 2-element lists. (You may
> _display_ such a list of lists in Table form, but such a display is not
> an object upon which you'd want to operate.)
>
> So do it like this (among other ways):
>
> pairs = {{1,3}, {2,4}, {3,6}, {4,1}, {5,3}, {6,2}, {7,5}, {8,2}};
> First /@ Select[pairs, Last[#] > 3 &]
>
> The Select function pulls out those pairs that satisfy your condition;
> the condition is specified by the "pure function" that's the 2nd
> argument to Select. Finally, mapping First (First /@ ...) onto the
> result gives the first member of each pair selected.
>
> On 1/11/12 4:18 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