python selective joining of list to get a string












0















Lets say I have a list in python like :



['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']


Is it possible to use list join to selectively add elements of a list. For example I add the full element0, but for other elements of the list I just add the last character(also I add the last character of element only if its length is3). so the string becomes:



"ann"+"e"+"f"+"r"+"a"+"n"+"k"= annefrank


The last element is not added as its not of length 3.
I can solve this using for loop, but would like to know if there is any optimized pythonic way of doing this or using join.



Thank you in anticipation.
AIA






python-3.x list







share|improve this question





























    0















    Lets say I have a list in python like :



    ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']


    Is it possible to use list join to selectively add elements of a list. For example I add the full element0, but for other elements of the list I just add the last character(also I add the last character of element only if its length is3). so the string becomes:



    "ann"+"e"+"f"+"r"+"a"+"n"+"k"= annefrank


    The last element is not added as its not of length 3.
    I can solve this using for loop, but would like to know if there is any optimized pythonic way of doing this or using join.



    Thank you in anticipation.
    AIA






    python-3.x list







    share|improve this question



























      0












      0








      0








      Lets say I have a list in python like :



      ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']


      Is it possible to use list join to selectively add elements of a list. For example I add the full element0, but for other elements of the list I just add the last character(also I add the last character of element only if its length is3). so the string becomes:



      "ann"+"e"+"f"+"r"+"a"+"n"+"k"= annefrank


      The last element is not added as its not of length 3.
      I can solve this using for loop, but would like to know if there is any optimized pythonic way of doing this or using join.



      Thank you in anticipation.
      AIA






      python-3.x list







      share|improve this question
















      Lets say I have a list in python like :



      ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']


      Is it possible to use list join to selectively add elements of a list. For example I add the full element0, but for other elements of the list I just add the last character(also I add the last character of element only if its length is3). so the string becomes:



      "ann"+"e"+"f"+"r"+"a"+"n"+"k"= annefrank


      The last element is not added as its not of length 3.
      I can solve this using for loop, but would like to know if there is any optimized pythonic way of doing this or using join.



      Thank you in anticipation.
      AIA






      python-3.x list




      python-3.x list






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 21 '18 at 19:44









      Franco Piccolo

      1,576712




      1,576712










      asked Nov 21 '18 at 16:31









      AIMCognitiveGurgaon BigDataAIMCognitiveGurgaon BigData

      124




      124
























          2 Answers
          2






          active

          oldest

          votes


















          0














          Since you have certain requirements you need to apply some custom logic anyway, regardless of the paradigm that you choose.



          I would use Python's functional tools for filtering the sequence:



          import operator
          
import functools
          

          
seq = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
          

          
functools.reduce(operator.add, (map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))), seq[0])
          
# gives annefrank


          The inner filter takes care of elements which are not of length 3, except the first element of the list. The map will return their last character and the reduce will apply add over them with first element of the list as the initial value.



          You can also do it with join if you prefer:



          seq[0]+''.join((map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))))
          
# gives annefrank


          You can also merge the filter into the map:



          seq[0]+''.join((map(lambda x: x[-1] if len(x)==3 else '', seq[1:])))


          As you see there are many ways to achieve what you want to do. However I will prefer map and filter over looping over a sequence since they have highly optimized implementations.






          share|improve this answer


























          • Thanks a lot for the solution..

            – AIMCognitiveGurgaon BigData
            Nov 22 '18 at 14:13



















          0














          You could build a list of the third letter from each item in the list:



              mylist = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
          
    thirdletters = [ x[2:3] for x in mylist ]


          (the final item in that new list will be an empty string because there is no third letter in 'nk') then collect those letters into a string by using join with an empty string as the filler:



              thirdstring = ''.join(thirdletters)


          and then finally add that string after the first two letters of the first item from the original list:



              result = mylist[0][:2] + thirdstring


          If that's too wordy, you can jam it all together into one statement:



              result = mylist[0][:2] + ''.join( [ x[2:3] for x in mylist ] )





          share|improve this answer























            Your Answer






            StackExchange.ifUsing("editor", function () {
            StackExchange.using("externalEditor", function () {
            StackExchange.using("snippets", function () {
            StackExchange.snippets.init();
            });
            });
            }, "code-snippets");

            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "1"
            };
            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',
            autoActivateHeartbeat: false,
            convertImagesToLinks: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            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%2fstackoverflow.com%2fquestions%2f53416584%2fpython-selective-joining-of-list-to-get-a-string%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









            0














            Since you have certain requirements you need to apply some custom logic anyway, regardless of the paradigm that you choose.



            I would use Python's functional tools for filtering the sequence:



            import operator
            
import functools
            

            
seq = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
            

            
functools.reduce(operator.add, (map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))), seq[0])
            
# gives annefrank


            The inner filter takes care of elements which are not of length 3, except the first element of the list. The map will return their last character and the reduce will apply add over them with first element of the list as the initial value.



            You can also do it with join if you prefer:



            seq[0]+''.join((map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))))
            
# gives annefrank


            You can also merge the filter into the map:



            seq[0]+''.join((map(lambda x: x[-1] if len(x)==3 else '', seq[1:])))


            As you see there are many ways to achieve what you want to do. However I will prefer map and filter over looping over a sequence since they have highly optimized implementations.






            share|improve this answer


























            • Thanks a lot for the solution..

              – AIMCognitiveGurgaon BigData
              Nov 22 '18 at 14:13
















            0














            Since you have certain requirements you need to apply some custom logic anyway, regardless of the paradigm that you choose.



            I would use Python's functional tools for filtering the sequence:



            import operator
            
import functools
            

            
seq = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
            

            
functools.reduce(operator.add, (map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))), seq[0])
            
# gives annefrank


            The inner filter takes care of elements which are not of length 3, except the first element of the list. The map will return their last character and the reduce will apply add over them with first element of the list as the initial value.



            You can also do it with join if you prefer:



            seq[0]+''.join((map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))))
            
# gives annefrank


            You can also merge the filter into the map:



            seq[0]+''.join((map(lambda x: x[-1] if len(x)==3 else '', seq[1:])))


            As you see there are many ways to achieve what you want to do. However I will prefer map and filter over looping over a sequence since they have highly optimized implementations.






            share|improve this answer


























            • Thanks a lot for the solution..

              – AIMCognitiveGurgaon BigData
              Nov 22 '18 at 14:13














            0












            0








            0







            Since you have certain requirements you need to apply some custom logic anyway, regardless of the paradigm that you choose.



            I would use Python's functional tools for filtering the sequence:



            import operator
            
import functools
            

            
seq = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
            

            
functools.reduce(operator.add, (map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))), seq[0])
            
# gives annefrank


            The inner filter takes care of elements which are not of length 3, except the first element of the list. The map will return their last character and the reduce will apply add over them with first element of the list as the initial value.



            You can also do it with join if you prefer:



            seq[0]+''.join((map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))))
            
# gives annefrank


            You can also merge the filter into the map:



            seq[0]+''.join((map(lambda x: x[-1] if len(x)==3 else '', seq[1:])))


            As you see there are many ways to achieve what you want to do. However I will prefer map and filter over looping over a sequence since they have highly optimized implementations.






            share|improve this answer















            Since you have certain requirements you need to apply some custom logic anyway, regardless of the paradigm that you choose.



            I would use Python's functional tools for filtering the sequence:



            import operator
            
import functools
            

            
seq = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
            

            
functools.reduce(operator.add, (map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))), seq[0])
            
# gives annefrank


            The inner filter takes care of elements which are not of length 3, except the first element of the list. The map will return their last character and the reduce will apply add over them with first element of the list as the initial value.



            You can also do it with join if you prefer:



            seq[0]+''.join((map(lambda x: x[-1], filter(lambda x: len(x)==3, seq[1:]))))
            
# gives annefrank


            You can also merge the filter into the map:



            seq[0]+''.join((map(lambda x: x[-1] if len(x)==3 else '', seq[1:])))


            As you see there are many ways to achieve what you want to do. However I will prefer map and filter over looping over a sequence since they have highly optimized implementations.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Nov 22 '18 at 15:41

























            answered Nov 22 '18 at 9:39









            Mehdi SadeghiMehdi Sadeghi

            2,7451726




            2,7451726













            • Thanks a lot for the solution..

              – AIMCognitiveGurgaon BigData
              Nov 22 '18 at 14:13



















            • Thanks a lot for the solution..

              – AIMCognitiveGurgaon BigData
              Nov 22 '18 at 14:13

















            Thanks a lot for the solution..

            – AIMCognitiveGurgaon BigData
            Nov 22 '18 at 14:13





            Thanks a lot for the solution..

            – AIMCognitiveGurgaon BigData
            Nov 22 '18 at 14:13













            0














            You could build a list of the third letter from each item in the list:



                mylist = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
            
    thirdletters = [ x[2:3] for x in mylist ]


            (the final item in that new list will be an empty string because there is no third letter in 'nk') then collect those letters into a string by using join with an empty string as the filler:



                thirdstring = ''.join(thirdletters)


            and then finally add that string after the first two letters of the first item from the original list:



                result = mylist[0][:2] + thirdstring


            If that's too wordy, you can jam it all together into one statement:



                result = mylist[0][:2] + ''.join( [ x[2:3] for x in mylist ] )





            share|improve this answer




























              0














              You could build a list of the third letter from each item in the list:



                  mylist = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
              
    thirdletters = [ x[2:3] for x in mylist ]


              (the final item in that new list will be an empty string because there is no third letter in 'nk') then collect those letters into a string by using join with an empty string as the filler:



                  thirdstring = ''.join(thirdletters)


              and then finally add that string after the first two letters of the first item from the original list:



                  result = mylist[0][:2] + thirdstring


              If that's too wordy, you can jam it all together into one statement:



                  result = mylist[0][:2] + ''.join( [ x[2:3] for x in mylist ] )





              share|improve this answer


























                0












                0








                0







                You could build a list of the third letter from each item in the list:



                    mylist = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
                
    thirdletters = [ x[2:3] for x in mylist ]


                (the final item in that new list will be an empty string because there is no third letter in 'nk') then collect those letters into a string by using join with an empty string as the filler:



                    thirdstring = ''.join(thirdletters)


                and then finally add that string after the first two letters of the first item from the original list:



                    result = mylist[0][:2] + thirdstring


                If that's too wordy, you can jam it all together into one statement:



                    result = mylist[0][:2] + ''.join( [ x[2:3] for x in mylist ] )





                share|improve this answer













                You could build a list of the third letter from each item in the list:



                    mylist = ['ann', 'nne', 'nef', 'efr', 'fra', 'ran', 'ank', 'nk']
                
    thirdletters = [ x[2:3] for x in mylist ]


                (the final item in that new list will be an empty string because there is no third letter in 'nk') then collect those letters into a string by using join with an empty string as the filler:



                    thirdstring = ''.join(thirdletters)


                and then finally add that string after the first two letters of the first item from the original list:



                    result = mylist[0][:2] + thirdstring


                If that's too wordy, you can jam it all together into one statement:



                    result = mylist[0][:2] + ''.join( [ x[2:3] for x in mylist ] )






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 22 '18 at 8:54









                ottomeisterottomeister

                2,39421117




                2,39421117






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Stack Overflow!


                    • 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%2fstackoverflow.com%2fquestions%2f53416584%2fpython-selective-joining-of-list-to-get-a-string%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

                    Paul Cézanne

                    Image
                    Pour l’article ayant un titre homophone, voir Sézanne. Paul Cézanne.mw-parser-output .entete.artiste{background-image:url("//upload.wikimedia.org/wikipedia/commons/f/f3/Picto_infobox_artiste.png")} Autoportrait vers 1861 Naissance 19 janvier 1839 Aix-en-Provence (France) Décès 22 octobre 1906 (à 67 ans) Aix-en-Provence (France) Nationalité Française Activité Peintre Formation Académie de Charles Suisse Maître Joseph Gilbert, Antoine Guillemet, Camille Pissarro Mouvement Impressionnisme postimpressionnisme Influencé par Eugène Delacroix, Gustave Courbet, Véronèse A influencé Braque, Picasso, Matisse Conjoint Hortense Fiquet (depuis 1886) Enfant Paul Cézanne  ( d ) Œuvres principales La Montagne Sainte-Victoire, Portrait de madame Cézanne signature modifier - modifier le code - modifier Wikidata Paul Cézanne , né le 19 janvier 1839 à Aix-en-Provence et mort le 22 octobre 1906 dans la mê...
                    Read more

                    UIScrollView CustomStickyHeader Resize height generates problems when scroll is too fast

                    Image
                    0 I have been trying for a while to create a UIViewController that has a CustomStickyHeader and a UITableView. The idea I have been following is use the UITableView scrolling for changing the header view with the value of the contentOffset. The layout for the ViewController (AlbumsViewController) looks like: The UItableView Scrolling functions from the delegate are implemented like that: func scrollViewDidScroll(_ scrollView: UIScrollView) { let endReached = contentTableView.contentOffset.y >= (contentTableView.contentSize.height - contentTableView.frame.size.height) let isUP = lastContentOffset > scrollView.contentOffset.y if scrollView.contentOffset.y < 0 { headerHeightConstraint.constant += abs(scrollView.contentOffset.y) } else{ if !endReached{ ...
                    Read more

                    Angular material date-picker (MatDatepicker) auto completes the date on focus out

                    Image
                    3 3 I am using angular material/mat-datepicker in my project and whenever the user enters one digit inside of it, and goes out of focus - the date picker is auto completing with a random date. Example Just enter 1 and go out of focus, or enter 5/5/20 The date picker is adding date automatically Update : Also I am using reactive forms and I'm validating the input with that approach Can I disable this ? angular datepicker angular-material angular6 angular-material-datetimepicker share | improve this question edited Nov 20 '18 at 13:21 ...
                    Read more