Selecting based on criterion on a single column












2












$begingroup$


I have an array that looks like M = {a, b, c, d}, where a, b, c, d are column vectors. I want to select rows from this array based on the elements in column c meeting a specified condition.



For example, if I have



M = {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"horse", 30, 1, 19},{"hippo", 99, 15,4}}


I want to take rows from this array based on the condition 



c[[i]] >= 10


How could this be done? Ideally I would like to use Select as this can retrieve the sublist.






list-manipulation filtering







share|improve this question











$endgroup$








  • 1




    $begingroup$
    Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
    $endgroup$
    – Somos
    8 hours ago
















2












$begingroup$


I have an array that looks like M = {a, b, c, d}, where a, b, c, d are column vectors. I want to select rows from this array based on the elements in column c meeting a specified condition.



For example, if I have



M = {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"horse", 30, 1, 19},{"hippo", 99, 15,4}}


I want to take rows from this array based on the condition 



c[[i]] >= 10


How could this be done? Ideally I would like to use Select as this can retrieve the sublist.






list-manipulation filtering







share|improve this question











$endgroup$








  • 1




    $begingroup$
    Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
    $endgroup$
    – Somos
    8 hours ago














2












2








2





$begingroup$


I have an array that looks like M = {a, b, c, d}, where a, b, c, d are column vectors. I want to select rows from this array based on the elements in column c meeting a specified condition.



For example, if I have



M = {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"horse", 30, 1, 19},{"hippo", 99, 15,4}}


I want to take rows from this array based on the condition 



c[[i]] >= 10


How could this be done? Ideally I would like to use Select as this can retrieve the sublist.






list-manipulation filtering







share|improve this question











$endgroup$




I have an array that looks like M = {a, b, c, d}, where a, b, c, d are column vectors. I want to select rows from this array based on the elements in column c meeting a specified condition.



For example, if I have



M = {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"horse", 30, 1, 19},{"hippo", 99, 15,4}}


I want to take rows from this array based on the condition 



c[[i]] >= 10


How could this be done? Ideally I would like to use Select as this can retrieve the sublist.






list-manipulation filtering




list-manipulation filtering






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 8 hours ago









m_goldberg

85.7k872196




85.7k872196










asked 8 hours ago









MKFMKF

1238




1238








  • 1




    $begingroup$
    Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
    $endgroup$
    – Somos
    8 hours ago














  • 1




    $begingroup$
    Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
    $endgroup$
    – Somos
    8 hours ago








1




1




$begingroup$
Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
$endgroup$
– Somos
8 hours ago




$begingroup$
Essentially a duplicate of Mathematica SE question 45951 "Select record when third column matches certain criterion".
$endgroup$
– Somos
8 hours ago










2 Answers
2






active

oldest

votes


















4












$begingroup$

Feels like a duplicate of a bunch of questions, you could probably find by searching this forum... Some basic structures:



Select[M, #[[3]] >= 3 &]



{{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




Cases[M,x_/;x[[3]]>=3]



{{"cat",21,10,1},{"dog",7,42,2},{"hippo",99,15,4}}







share|improve this answer









$endgroup$





















    3












    $begingroup$

    Pick[M, UnitStep[M[[All, 3]] - 10], 1]



    {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




    More general, you may use



    check = # >= 10 &;
    
Pick[M, check /@ M[[All, 3]]]





    share|improve this answer











    $endgroup$













    • $begingroup$
      Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
      $endgroup$
      – MKF
      8 hours ago











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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    4












    $begingroup$

    Feels like a duplicate of a bunch of questions, you could probably find by searching this forum... Some basic structures:



    Select[M, #[[3]] >= 3 &]



    {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




    Cases[M,x_/;x[[3]]>=3]



    {{"cat",21,10,1},{"dog",7,42,2},{"hippo",99,15,4}}







    share|improve this answer









    $endgroup$


















      4












      $begingroup$

      Feels like a duplicate of a bunch of questions, you could probably find by searching this forum... Some basic structures:



      Select[M, #[[3]] >= 3 &]



      {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




      Cases[M,x_/;x[[3]]>=3]



      {{"cat",21,10,1},{"dog",7,42,2},{"hippo",99,15,4}}







      share|improve this answer









      $endgroup$
















        4












        4








        4





        $begingroup$

        Feels like a duplicate of a bunch of questions, you could probably find by searching this forum... Some basic structures:



        Select[M, #[[3]] >= 3 &]



        {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




        Cases[M,x_/;x[[3]]>=3]



        {{"cat",21,10,1},{"dog",7,42,2},{"hippo",99,15,4}}







        share|improve this answer









        $endgroup$



        Feels like a duplicate of a bunch of questions, you could probably find by searching this forum... Some basic structures:



        Select[M, #[[3]] >= 3 &]



        {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




        Cases[M,x_/;x[[3]]>=3]



        {{"cat",21,10,1},{"dog",7,42,2},{"hippo",99,15,4}}








        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 8 hours ago









        Vitaliy KaurovVitaliy Kaurov

        57.2k6161280




        57.2k6161280























            3












            $begingroup$

            Pick[M, UnitStep[M[[All, 3]] - 10], 1]



            {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




            More general, you may use



            check = # >= 10 &;
            
Pick[M, check /@ M[[All, 3]]]





            share|improve this answer











            $endgroup$













            • $begingroup$
              Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
              $endgroup$
              – MKF
              8 hours ago
















            3












            $begingroup$

            Pick[M, UnitStep[M[[All, 3]] - 10], 1]



            {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




            More general, you may use



            check = # >= 10 &;
            
Pick[M, check /@ M[[All, 3]]]





            share|improve this answer











            $endgroup$













            • $begingroup$
              Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
              $endgroup$
              – MKF
              8 hours ago














            3












            3








            3





            $begingroup$

            Pick[M, UnitStep[M[[All, 3]] - 10], 1]



            {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




            More general, you may use



            check = # >= 10 &;
            
Pick[M, check /@ M[[All, 3]]]





            share|improve this answer











            $endgroup$



            Pick[M, UnitStep[M[[All, 3]] - 10], 1]



            {{"cat", 21, 10, 1}, {"dog", 7, 42, 2}, {"hippo", 99, 15, 4}}




            More general, you may use



            check = # >= 10 &;
            
Pick[M, check /@ M[[All, 3]]]






            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited 5 hours ago

























            answered 8 hours ago









            Henrik SchumacherHenrik Schumacher

            52.5k471148




            52.5k471148












            • $begingroup$
              Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
              $endgroup$
              – MKF
              8 hours ago


















            • $begingroup$
              Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
              $endgroup$
              – MKF
              8 hours ago
















            $begingroup$
            Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
            $endgroup$
            – MKF
            8 hours ago




            $begingroup$
            Thanks Henrik; this technique wouldn't work if I exchange entries to arbitrary arrays, so is there perhaps a generalisation? I was thinking something like Select[M, (#[[All, 3]] >=10) &] - then (if it worked) the type of element wouldn't matter so much i.e. It could generalise to more complicated criteria
            $endgroup$
            – MKF
            8 hours ago


















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