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I have a huge list that looks like this:

list = {8, 12, 201, 0.001, 3, 7, 100 
  (InterpolatingFunction[{{0., 0.0018}},"<>"][2916/35] + 
   InterpolatingFunction[{{0., 0.0018}}, "<>"][2916/35]), 
  23, 44, 11, -0.002}

I want to extract only the numbers, specifically the numbers around 10. I tried using this Select[list, _?(7 <= # <= 13 &)] but it returns an empty list. I think this happens because the list has both numbers and the 100 (InterpolatingFunction... that I want to ignore. I would also be happy just to extract ALL numbers hence ignoring the 100(InterpolatingFunction... elements.

Could you give me some tip please?

m_goldberg
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Sos
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    You can use Select[..., NumberQ[#] && 7 <= # <= 13 & ] – b.gates.you.know.what Mar 13 '13 at 09:54
  • Thank you so much! That makes it! Should I delete the question? – Sos Mar 13 '13 at 10:00
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    You should never delete a question because you got an answer (only if your question was over-the-top stupid). It may be useful to others as well. – Sjoerd C. de Vries Mar 13 '13 at 10:13
  • Why is that InterpolatingFunctionthere in the first place? Wouldn't you like to have that evaluated to a real number? – Sjoerd C. de Vries Mar 13 '13 at 10:15
  • @Sjoerd: list comes as result of integrating a system using NDSolve considering around 4000 combinations of parameters. Some of those combinations do not yield a solution for the integration.. If possible, yes, I would like to have it evaluated to a real number, but the numerical integration doesn't finish until the endtime I allocated, and the endtime of the InterpolatingFunction is far from the desired (e.g. 0.018429 out of the desired 83.3). – Sos Mar 13 '13 at 10:58
  • @sosi OK, I see. – Sjoerd C. de Vries Mar 13 '13 at 11:08

1 Answers1

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Select wants a function as second argument, not a pattern. You can either use Cases or Select with a pure function:

Cases[list, _?(7 <= # <= 13 &)]

Select[list, (7 <= # <= 13)&]
m_goldberg
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Albert Retey
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  • One more thing:

    if I want to select the elements of another list

    otherlist={{1/10,1,1/100,10},{1/100,1,1/100,10},...}

    that were used as arguments to obtain

    list={8,12,201,0.001,3,7,100(InterpolatingFunction[{{0.,0.0018}},"<>"][2916/35]+InterpolatingFunction[{{0.,0.0018}},"<>"][2916/35]),23,44,11,-0.002}

    I thought I could use Pick[otherlist,list,NumberQ[#]&&7<=#<=13&]. Yet, it isn't working and returns that both lists have incompatible shapes. But both lists have the same length..

     – Sos Mar 13 '13 at 10:09
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    @Sosi: same problem the other way round: Pick wants, as Cases, a pattern, not a function. Pick[otherlist,list,_?(NumberQ[#]&&7<=#<=13&)] should work, if both lists really have the same structure. Something that might be a problem is that Pick applies the check to all levels of list, so depending on what exactly is the content you might see the shapes-warning. It then probably is better to create a "selection" list independently: Pick[otherlist, (NumberQ[#] && 7 <= # <= 13) & /@ list] – Albert Retey Mar 13 '13 at 10:22
  • I had tried your first suggestion before, but was getting that structure error. The second suggestion works perfectly, I had not thought about using a map! Thanks! – Sos Mar 13 '13 at 10:31
  • @Sosi: here is another question which has more information about what I think is the deeper reason for the "incompatible shapes" warning, in case you are interested... – Albert Retey Mar 13 '13 at 17:50