Eliminate empty elements from a list with a specific pattern












3












$begingroup$


I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:



list={"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"}


and I need to obtain



list={"a12-b11-{1}", "d33-c22-{2}"}


The list was created using



list =  Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]],
{i, 1, 4}, {j, 1, 4}], 1]


and for some values it writtes {} because there is not a value equal to $0.5$. Until now I have been able to do it term by term as



list//."a11-b11-{}"-> Sequence


but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.










share|improve this question











$endgroup$












  • $begingroup$
    Have a look at DeleteCases and StringMatchQ or StringContainsQ.
    $endgroup$
    – b.gatessucks
    yesterday










  • $begingroup$
    I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
    $endgroup$
    – Roman
    yesterday












  • $begingroup$
    @b.gatessucks Thank you, I will look those option in Mathematica.
    $endgroup$
    – mors
    yesterday










  • $begingroup$
    @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
    $endgroup$
    – mors
    yesterday
















3












$begingroup$


I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:



list={"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"}


and I need to obtain



list={"a12-b11-{1}", "d33-c22-{2}"}


The list was created using



list =  Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]],
{i, 1, 4}, {j, 1, 4}], 1]


and for some values it writtes {} because there is not a value equal to $0.5$. Until now I have been able to do it term by term as



list//."a11-b11-{}"-> Sequence


but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.










share|improve this question











$endgroup$












  • $begingroup$
    Have a look at DeleteCases and StringMatchQ or StringContainsQ.
    $endgroup$
    – b.gatessucks
    yesterday










  • $begingroup$
    I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
    $endgroup$
    – Roman
    yesterday












  • $begingroup$
    @b.gatessucks Thank you, I will look those option in Mathematica.
    $endgroup$
    – mors
    yesterday










  • $begingroup$
    @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
    $endgroup$
    – mors
    yesterday














3












3








3


1



$begingroup$


I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:



list={"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"}


and I need to obtain



list={"a12-b11-{1}", "d33-c22-{2}"}


The list was created using



list =  Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]],
{i, 1, 4}, {j, 1, 4}], 1]


and for some values it writtes {} because there is not a value equal to $0.5$. Until now I have been able to do it term by term as



list//."a11-b11-{}"-> Sequence


but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.










share|improve this question











$endgroup$




I am really new in this patterns part of Mathematica. Basically what I need to do is eliminate null elements from a list but that has a specific name before the empty element. For example, my list is:



list={"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"}


and I need to obtain



list={"a12-b11-{1}", "d33-c22-{2}"}


The list was created using



list =  Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> 
ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]],
{i, 1, 4}, {j, 1, 4}], 1]


and for some values it writtes {} because there is not a value equal to $0.5$. Until now I have been able to do it term by term as



list//."a11-b11-{}"-> Sequence


but the real list contains a lot of elements and could be almost impossible to do it that way to solve the problem. I think my main problem is that I am not sure how to specify the pattern search (something like " *-name " in gnu/linux). Is there a wise way to do this?. Thanks in advance.







list-manipulation filtering






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited yesterday









Roman

4,89011130




4,89011130










asked yesterday









morsmors

496




496












  • $begingroup$
    Have a look at DeleteCases and StringMatchQ or StringContainsQ.
    $endgroup$
    – b.gatessucks
    yesterday










  • $begingroup$
    I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
    $endgroup$
    – Roman
    yesterday












  • $begingroup$
    @b.gatessucks Thank you, I will look those option in Mathematica.
    $endgroup$
    – mors
    yesterday










  • $begingroup$
    @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
    $endgroup$
    – mors
    yesterday


















  • $begingroup$
    Have a look at DeleteCases and StringMatchQ or StringContainsQ.
    $endgroup$
    – b.gatessucks
    yesterday










  • $begingroup$
    I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
    $endgroup$
    – Roman
    yesterday












  • $begingroup$
    @b.gatessucks Thank you, I will look those option in Mathematica.
    $endgroup$
    – mors
    yesterday










  • $begingroup$
    @Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
    $endgroup$
    – mors
    yesterday
















$begingroup$
Have a look at DeleteCases and StringMatchQ or StringContainsQ.
$endgroup$
– b.gatessucks
yesterday




$begingroup$
Have a look at DeleteCases and StringMatchQ or StringContainsQ.
$endgroup$
– b.gatessucks
yesterday












$begingroup$
I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
$endgroup$
– Roman
yesterday






$begingroup$
I think it would be more efficient to first filter out the unwanted cases in the int function, and then construct strings only from the remaining ones.
$endgroup$
– Roman
yesterday














$begingroup$
@b.gatessucks Thank you, I will look those option in Mathematica.
$endgroup$
– mors
yesterday




$begingroup$
@b.gatessucks Thank you, I will look those option in Mathematica.
$endgroup$
– mors
yesterday












$begingroup$
@Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
$endgroup$
– mors
yesterday




$begingroup$
@Roman You are right, but I am new ih this cases stuf in Mathematica and I did no know how to do it when I created the list.
$endgroup$
– mors
yesterday










2 Answers
2






active

oldest

votes


















7












$begingroup$

If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:



list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
Select[list, Not@*StringMatchQ[__ ~~ "{}"]]



{"a12-b11-{1}", "d33-c22-{2}"}




You could also Select before making the strings:



L = DeleteCases[
Flatten[
Table[
{namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1]},
{i, 4}, {j, 4}],
1],
{_, _, {}}];


and then make these into strings:



StringRiffle[ToString /@ #, "-"] & /@ L


I can't check this because you didn't supply functioning code.






share|improve this answer











$endgroup$













  • $begingroup$
    Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
    $endgroup$
    – mors
    yesterday





















1












$begingroup$

In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using



list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
Select[list, Not@*StringEndsQ["{}"]]


instead.






share|improve this answer









$endgroup$














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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    7












    $begingroup$

    If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:



    list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
    Select[list, Not@*StringMatchQ[__ ~~ "{}"]]



    {"a12-b11-{1}", "d33-c22-{2}"}




    You could also Select before making the strings:



    L = DeleteCases[
    Flatten[
    Table[
    {namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1]},
    {i, 4}, {j, 4}],
    1],
    {_, _, {}}];


    and then make these into strings:



    StringRiffle[ToString /@ #, "-"] & /@ L


    I can't check this because you didn't supply functioning code.






    share|improve this answer











    $endgroup$













    • $begingroup$
      Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
      $endgroup$
      – mors
      yesterday


















    7












    $begingroup$

    If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:



    list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
    Select[list, Not@*StringMatchQ[__ ~~ "{}"]]



    {"a12-b11-{1}", "d33-c22-{2}"}




    You could also Select before making the strings:



    L = DeleteCases[
    Flatten[
    Table[
    {namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1]},
    {i, 4}, {j, 4}],
    1],
    {_, _, {}}];


    and then make these into strings:



    StringRiffle[ToString /@ #, "-"] & /@ L


    I can't check this because you didn't supply functioning code.






    share|improve this answer











    $endgroup$













    • $begingroup$
      Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
      $endgroup$
      – mors
      yesterday
















    7












    7








    7





    $begingroup$

    If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:



    list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
    Select[list, Not@*StringMatchQ[__ ~~ "{}"]]



    {"a12-b11-{1}", "d33-c22-{2}"}




    You could also Select before making the strings:



    L = DeleteCases[
    Flatten[
    Table[
    {namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1]},
    {i, 4}, {j, 4}],
    1],
    {_, _, {}}];


    and then make these into strings:



    StringRiffle[ToString /@ #, "-"] & /@ L


    I can't check this because you didn't supply functioning code.






    share|improve this answer











    $endgroup$



    If the list elements are strings, as it appears after your comment, you can use Select with a string pattern:



    list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
    Select[list, Not@*StringMatchQ[__ ~~ "{}"]]



    {"a12-b11-{1}", "d33-c22-{2}"}




    You could also Select before making the strings:



    L = DeleteCases[
    Flatten[
    Table[
    {namea[[i]], nameb[[j]], Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1]},
    {i, 4}, {j, 4}],
    1],
    {_, _, {}}];


    and then make these into strings:



    StringRiffle[ToString /@ #, "-"] & /@ L


    I can't check this because you didn't supply functioning code.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited yesterday

























    answered yesterday









    RomanRoman

    4,89011130




    4,89011130












    • $begingroup$
      Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
      $endgroup$
      – mors
      yesterday




















    • $begingroup$
      Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
      $endgroup$
      – mors
      yesterday


















    $begingroup$
    Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
    $endgroup$
    – mors
    yesterday






    $begingroup$
    Thank you, I forgot to specify the way the list is created. I create the list as 'list = Flatten[Table[ ToString[namea[[i]] <> "-" <> nameb[[j]] <> "-" <> ToString[ Select[int[i, j, 0.5], Abs[#] == 0.5 &, 1] ]], {i, 1, 4}, {j, 1, 4}], 1] '
    $endgroup$
    – mors
    yesterday













    1












    $begingroup$

    In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using



    list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
    Select[list, Not@*StringEndsQ["{}"]]


    instead.






    share|improve this answer









    $endgroup$


















      1












      $begingroup$

      In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using



      list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
      Select[list, Not@*StringEndsQ["{}"]]


      instead.






      share|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using



        list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
        Select[list, Not@*StringEndsQ["{}"]]


        instead.






        share|improve this answer









        $endgroup$



        In 10.1, two functions were added to handle a pair of very common cases: StringStartsQ and StringEndsQ which return True if the string matches a pattern at the beginning or end, respectively. So, while Roman's answer gives you the full general form, most of the pattern can be eliminated by using



        list = {"a11-b11-{}", "a12-b11-{1}", "c11-d22-{}", "d33-c22-{2}"};
        Select[list, Not@*StringEndsQ["{}"]]


        instead.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered yesterday









        rcollyerrcollyer

        28.6k674166




        28.6k674166






























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