selective deletions from list











up vote
2
down vote

favorite












I have a list:



lis = {{"b","x","d"},{"a","z","b"},{"a","x","b"},{"a","x","c"},{"b","z","d"}}


Certain consecutive elements of this list will have identical first and last members (in this example, "a" and "b" in lis[[2]] and lis[[3]]) and I would like to delete the element that has "x" as its middle element, to give:



res = {{"b","x","d"},{"a","z","b"},{"a","x","c"},{"b","z","d"}}


It seems like a job for SequenceCases, but am having no luck.






list-manipulation







share|improve this question


















  • 1




    elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
    – J42161217
    2 hours ago










  • Take a look at DeleteDuplicatesBy.
    – Kuba♦
    2 hours ago












  • Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
    – That Gravity Guy
    2 hours ago















up vote
2
down vote

favorite












I have a list:



lis = {{"b","x","d"},{"a","z","b"},{"a","x","b"},{"a","x","c"},{"b","z","d"}}


Certain consecutive elements of this list will have identical first and last members (in this example, "a" and "b" in lis[[2]] and lis[[3]]) and I would like to delete the element that has "x" as its middle element, to give:



res = {{"b","x","d"},{"a","z","b"},{"a","x","c"},{"b","z","d"}}


It seems like a job for SequenceCases, but am having no luck.






list-manipulation







share|improve this question


















  • 1




    elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
    – J42161217
    2 hours ago










  • Take a look at DeleteDuplicatesBy.
    – Kuba♦
    2 hours ago












  • Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
    – That Gravity Guy
    2 hours ago













up vote
2
down vote

favorite









up vote
2
down vote

favorite











I have a list:



lis = {{"b","x","d"},{"a","z","b"},{"a","x","b"},{"a","x","c"},{"b","z","d"}}


Certain consecutive elements of this list will have identical first and last members (in this example, "a" and "b" in lis[[2]] and lis[[3]]) and I would like to delete the element that has "x" as its middle element, to give:



res = {{"b","x","d"},{"a","z","b"},{"a","x","c"},{"b","z","d"}}


It seems like a job for SequenceCases, but am having no luck.






list-manipulation







share|improve this question













I have a list:



lis = {{"b","x","d"},{"a","z","b"},{"a","x","b"},{"a","x","c"},{"b","z","d"}}


Certain consecutive elements of this list will have identical first and last members (in this example, "a" and "b" in lis[[2]] and lis[[3]]) and I would like to delete the element that has "x" as its middle element, to give:



res = {{"b","x","d"},{"a","z","b"},{"a","x","c"},{"b","z","d"}}


It seems like a job for SequenceCases, but am having no luck.






list-manipulation




list-manipulation






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 2 hours ago









Suite401

969312




969312








  • 1




    elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
    – J42161217
    2 hours ago










  • Take a look at DeleteDuplicatesBy.
    – Kuba♦
    2 hours ago












  • Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
    – That Gravity Guy
    2 hours ago














  • 1




    elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
    – J42161217
    2 hours ago










  • Take a look at DeleteDuplicatesBy.
    – Kuba♦
    2 hours ago












  • Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
    – That Gravity Guy
    2 hours ago








1




1




elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
– J42161217
2 hours ago




elements 1 and 5 also have identical first and last members...Shouldn't you erase the first element, too?
– J42161217
2 hours ago












Take a look at DeleteDuplicatesBy.
– Kuba♦
2 hours ago






Take a look at DeleteDuplicatesBy.
– Kuba♦
2 hours ago














Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
– That Gravity Guy
2 hours ago




Another approach could be to start with Split[lis, #1[[1]] == #2[[1]] && #1[[3]] == #2[[3]] &] to group the consecutive elements.
– That Gravity Guy
2 hours ago










2 Answers
2






active

oldest

votes

















up vote
6
down vote













SequenceReplace[lis, {OrderlessPatternSequence[{a_, "x", c_}, {a_, b_, c_}]} :> {a, b, c}]



{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}







share|improve this answer




























    up vote
    0
    down vote













    One approach is to look at the differences between adjacent elements, find those which equal {0,0,x_}, and remove them from the list.



    lis[[Complement[Range[Length[lis]],Flatten@Position[Differences[lis], {0, 0, x_}]]]]
    

    
{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}





    share|improve this answer





















      Your Answer





      StackExchange.ifUsing("editor", function () {
      return StackExchange.using("mathjaxEditing", function () {
      StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
      StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
      });
      });
      }, "mathjax-editing");

      StackExchange.ready(function() {
      var channelOptions = {
      tags: "".split(" "),
      id: "387"
      };
      initTagRenderer("".split(" "), "".split(" "), channelOptions);

      StackExchange.using("externalEditor", function() {
      // Have to fire editor after snippets, if snippets enabled
      if (StackExchange.settings.snippets.snippetsEnabled) {
      StackExchange.using("snippets", function() {
      createEditor();
      });
      }
      else {
      createEditor();
      }
      });

      function createEditor() {
      StackExchange.prepareEditor({
      heartbeatType: 'answer',
      convertImagesToLinks: false,
      noModals: true,
      showLowRepImageUploadWarning: true,
      reputationToPostImages: null,
      bindNavPrevention: true,
      postfix: "",
      imageUploader: {
      brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
      contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
      allowUrls: true
      },
      onDemand: true,
      discardSelector: ".discard-answer"
      ,immediatelyShowMarkdownHelp:true
      });


      }
      });














      draft saved

      draft discarded


















      StackExchange.ready(
      function () {
      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f187725%2fselective-deletions-from-list%23new-answer', 'question_page');
      }
      );

      Post as a guest















      Required, but never shown

























      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      6
      down vote













      SequenceReplace[lis, {OrderlessPatternSequence[{a_, "x", c_}, {a_, b_, c_}]} :> {a, b, c}]



      {{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}







      share|improve this answer

























        up vote
        6
        down vote













        SequenceReplace[lis, {OrderlessPatternSequence[{a_, "x", c_}, {a_, b_, c_}]} :> {a, b, c}]



        {{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}







        share|improve this answer























          up vote
          6
          down vote










          up vote
          6
          down vote









          SequenceReplace[lis, {OrderlessPatternSequence[{a_, "x", c_}, {a_, b_, c_}]} :> {a, b, c}]



          {{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}







          share|improve this answer












          SequenceReplace[lis, {OrderlessPatternSequence[{a_, "x", c_}, {a_, b_, c_}]} :> {a, b, c}]



          {{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}








          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 2 hours ago









          kglr

          175k9197402




          175k9197402






















              up vote
              0
              down vote













              One approach is to look at the differences between adjacent elements, find those which equal {0,0,x_}, and remove them from the list.



              lis[[Complement[Range[Length[lis]],Flatten@Position[Differences[lis], {0, 0, x_}]]]]
              

              
{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}





              share|improve this answer

























                up vote
                0
                down vote













                One approach is to look at the differences between adjacent elements, find those which equal {0,0,x_}, and remove them from the list.



                lis[[Complement[Range[Length[lis]],Flatten@Position[Differences[lis], {0, 0, x_}]]]]
                

                
{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}





                share|improve this answer























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  One approach is to look at the differences between adjacent elements, find those which equal {0,0,x_}, and remove them from the list.



                  lis[[Complement[Range[Length[lis]],Flatten@Position[Differences[lis], {0, 0, x_}]]]]
                  

                  
{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}





                  share|improve this answer












                  One approach is to look at the differences between adjacent elements, find those which equal {0,0,x_}, and remove them from the list.



                  lis[[Complement[Range[Length[lis]],Flatten@Position[Differences[lis], {0, 0, x_}]]]]
                  

                  
{{"b", "x", "d"}, {"a", "z", "b"}, {"a", "x", "c"}, {"b", "z", "d"}}






                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 19 mins ago









                  bill s

                  52.5k375149




                  52.5k375149






























                      draft saved

                      draft discarded




















































                      Thanks for contributing an answer to Mathematica Stack Exchange!


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid …



                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.


                      Use MathJax to format equations. MathJax reference.


                      To learn more, see our tips on writing great answers.





                      Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


                      Please pay close attention to the following guidance:


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid …



                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.


                      To learn more, see our tips on writing great answers.




                      draft saved


                      draft discarded














                      StackExchange.ready(
                      function () {
                      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f187725%2fselective-deletions-from-list%23new-answer', 'question_page');
                      }
                      );

                      Post as a guest















                      Required, but never shown





















































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown

































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown







                      -

                      Popular posts from this blog

                      flock() on closed filehandle LOCK_FILE at /usr/bin/apt-mirror

                      Image
                      0 I recently upgraded an Ubuntu 16.04 virtual machine to 18.04. I regularly use this VM to run apt-mirror at school on their high-speed internet, then rsync these files to my rack-mount server at home for updating multiple computers at home without wasting the tiny amount of bandwidth I have there. Since updating I can't get apt-mirror to run on my VM. It keeps giving the error: flock() on closed filehandle LOCK_FILE at /usr/bin/apt-mirror line 214 immediately followed by: apt-mirror is already running, exiting at /usr/bin/apt-mirror line 217 apt-mirror is NOT running, and does not have a cron job. I've tried rebooting, and even looked for the old-style lockfile to delete, but I guess that method is no longer used. Is there some way to force unlock this so I can run apt-mirror? UPDATE: So... I f
                      Read more

                      Mangá

                      Image
                        Nota:  Não confundir com Manga. Mangás e Animes Mangá Mangaká • Tankōbon Film comic La nouvelle manga Mangá original em inglês Anime História Animação influenciada por animes • Filler • OVA • Seiyū Públicos Kodomo • Shōjo • Shōnen Josei • Seinen Gêneros Mahō shōjo • Mecha • Harém Ecchi • Hentai ( Yaoi • Yuri Futanari • Shotacon • Lolicon Toddlercon ) Termos Bishōjo • Chibi • Fan service Gaiden • Kawaii • Kaitō • Light novel Mahō shōnen • Moe (antropomorfismo • Kemonomimi Nekomimi ) • Super deformed Omake • Tsundere • Yonkoma Listas Mangás • Animes • Ecchi • Mangaka • Estúdios • Revistas Fãs ( otaku ) Anime Music Video Convenções • Cosplay Dōjinshi • Fansub • Fandub • Fujoshi OS-tan • Scanlation Portal de Anime e mangá v d e O mangá (português brasileiro) ou manga (português europeu) [ 1 ] (em japonês: 漫画 , manga ? , lit. “história em quadrinhos”) , é a
                      Read more

                       ⁒  ․,‪⁊‑⁙ ⁖, ⁇‒※‌, †,⁖‗‌⁝    ‾‸⁘,‖⁔⁣,⁂‾
”‑,‥–,‬ ,⁀‹⁋‴⁑ ‒ ,‴⁋”‼ ⁨,‷⁔„ ‰′,‐‚ ‥‡‎“‷⁃⁨⁅⁣,⁔
⁇‘⁔⁡⁏⁌⁡‿‶‏⁨ ⁣⁕⁖⁨⁩⁥‽⁀  ‴‬⁜‟ ⁃‣‧⁕‮ …‍⁨‴ ⁩,⁚⁖‫ ,‵ ⁀,‮⁝‣‣ ⁑  ⁂– ․, ‾‽ ‏⁁“⁗‸ ‾… ‹‡⁌⁎‸‘ ‡⁏⁌‪ ‵⁛ ‎⁨ ―⁦⁤⁄⁕

                      ⁉…‧ ⁩,“⁡‹⁃‽⁞•,⁠‚  ⁓⁎  ⁜ ‴ ⁥⁡⁎‭,‍‑⁁⁌⁦ ⁁‟⁙‥‒“⁈ ,‪⁧ ⁙‿⁇⁦,⁝‘ ⁎“⁘‫‪,‗‹‛‹⁒  ⁇⁄‗‒•“⁇   ‐ ⁂
‘‛, ‶⁦ ⁇ ​⁞‧ 
,⁏ …‹–⁗⁡⁘⁄ ‏‿‬‟″ ‏⁢⁦⁗⁚⁝‬⁢⁏,⁧″⁍′‖⁂※⁄‘– ‵⁡ ‭⁢⁚,⁅‧,‼‛⁗,⁡⁗“⁔⁃⁍‷⁏‗‱⁌‚  
•⁝ ‚‒ ‥‰  ′⁌, ⁄, ⁛—‭‑”⁂,⁑ ‡⁨‴⁖⁙…,‑, ,⁎,․‣‥  ‴‎⁎,″‛⁎‭‿ ⁤ ‷‾‼‖,⁠⁊‾,⁦“‗‑‌†,⁙,†⁝′ 
,―‚․‘, ⁢  ‿‌,⁀„‣,⁌,‭‖ ⁆“‪,―  ⁀ ⁃,
‷⁥,​,‟‗⁄⁉⁐⁗―
,‮⁢⁩⁆⁣‹‭⁅ ⁝‾‏‭⁖ ⁕⁄‷,†‟‒ ⁣‹,​…​,⁤⁂⁨‮⁎⁙–‟‼ ⁍‱‱,‽,‫‽‣ ⁒,⁨ ⁄ ⁝”„‿‑‎⁈‿
 ⁀‛‼‟ ⁑“,⁩​ ‒
–⁡…⁢ ⁂ ⁈⁎,‵‡,⁛,,‱⁧⁋,․‬⁄ “,⁄‴⁊  ‗―,‵⁙⁔—⁀ —  ⁀‬‬ ‒⁋‼⁀― ,⁌′ ‍‶ ’
                      Read more