Count elements (rows) in group of a data table [duplicate]











up vote
0
down vote

favorite













This question already has an answer here:




  • Count number of rows matching a criteria

    6 answers




I have table (dt) which has several columns.



  X__1 First Name  Last Name Gender       Country Age       Date   Id

   1:    1      Dulce      Abril Female United States  32 15/10/2017 1562

   2:    2       Mara  Hashimoto Female Great Britain  25 16/08/2016 1582

   3:    3     Philip       Gent   Male        France  36 21/05/2015 2587

   4:    4   Kathleen     Hanner Female United States  25 15/10/2017 3549

   5:    5    Nereida    Magwood Female United States  58 16/08/2016 2468


I want to count the number of rows which has Country = "France" and Age >32.



I used the following command which gives me the result, but i need to count the number of rows in the result. What is the command to do it?



dt[Country == 'France' & Age > 32]





r







share|improve this question













marked as duplicate by Community♦ Nov 22 at 9:45


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.



















    up vote
    0
    down vote

    favorite













    This question already has an answer here:




    • Count number of rows matching a criteria

      6 answers




    I have table (dt) which has several columns.



      X__1 First Name  Last Name Gender       Country Age       Date   Id
    
   1:    1      Dulce      Abril Female United States  32 15/10/2017 1562
    
   2:    2       Mara  Hashimoto Female Great Britain  25 16/08/2016 1582
    
   3:    3     Philip       Gent   Male        France  36 21/05/2015 2587
    
   4:    4   Kathleen     Hanner Female United States  25 15/10/2017 3549
    
   5:    5    Nereida    Magwood Female United States  58 16/08/2016 2468


    I want to count the number of rows which has Country = "France" and Age >32.



    I used the following command which gives me the result, but i need to count the number of rows in the result. What is the command to do it?



    dt[Country == 'France' & Age > 32]





    r







    share|improve this question













    marked as duplicate by Community♦ Nov 22 at 9:45


    This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite












      This question already has an answer here:




      • Count number of rows matching a criteria

        6 answers




      I have table (dt) which has several columns.



        X__1 First Name  Last Name Gender       Country Age       Date   Id
      
   1:    1      Dulce      Abril Female United States  32 15/10/2017 1562
      
   2:    2       Mara  Hashimoto Female Great Britain  25 16/08/2016 1582
      
   3:    3     Philip       Gent   Male        France  36 21/05/2015 2587
      
   4:    4   Kathleen     Hanner Female United States  25 15/10/2017 3549
      
   5:    5    Nereida    Magwood Female United States  58 16/08/2016 2468


      I want to count the number of rows which has Country = "France" and Age >32.



      I used the following command which gives me the result, but i need to count the number of rows in the result. What is the command to do it?



      dt[Country == 'France' & Age > 32]





      r







      share|improve this question














      This question already has an answer here:




      • Count number of rows matching a criteria

        6 answers




      I have table (dt) which has several columns.



        X__1 First Name  Last Name Gender       Country Age       Date   Id
      
   1:    1      Dulce      Abril Female United States  32 15/10/2017 1562
      
   2:    2       Mara  Hashimoto Female Great Britain  25 16/08/2016 1582
      
   3:    3     Philip       Gent   Male        France  36 21/05/2015 2587
      
   4:    4   Kathleen     Hanner Female United States  25 15/10/2017 3549
      
   5:    5    Nereida    Magwood Female United States  58 16/08/2016 2468


      I want to count the number of rows which has Country = "France" and Age >32.



      I used the following command which gives me the result, but i need to count the number of rows in the result. What is the command to do it?



      dt[Country == 'France' & Age > 32]




      This question already has an answer here:




      • Count number of rows matching a criteria

        6 answers







      r




      r






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 21 at 22:48









      Malintha

      1,24862652




      1,24862652




      marked as duplicate by Community♦ Nov 22 at 9:45


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.






      marked as duplicate by Community♦ Nov 22 at 9:45


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


























          2 Answers
          2






          active

          oldest

          votes

















          up vote
          2
          down vote



          accepted










          use the function nrow()



          nrow(dt[Country == 'France' & Age > 32])





          share|improve this answer




























            up vote
            1
            down vote













            nrow() is simplest, but if you want to do it using data.table syntax:



            dt[Country == 'France' & Age > 32, (.N)]





            share|improve this answer




























              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes








              up vote
              2
              down vote



              accepted










              use the function nrow()



              nrow(dt[Country == 'France' & Age > 32])





              share|improve this answer

























                up vote
                2
                down vote



                accepted










                use the function nrow()



                nrow(dt[Country == 'France' & Age > 32])





                share|improve this answer























                  up vote
                  2
                  down vote



                  accepted







                  up vote
                  2
                  down vote



                  accepted






                  use the function nrow()



                  nrow(dt[Country == 'France' & Age > 32])





                  share|improve this answer












                  use the function nrow()



                  nrow(dt[Country == 'France' & Age > 32])






                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 21 at 22:54









                  alex_danielssen

                  1096




                  1096
























                      up vote
                      1
                      down vote













                      nrow() is simplest, but if you want to do it using data.table syntax:



                      dt[Country == 'France' & Age > 32, (.N)]





                      share|improve this answer

























                        up vote
                        1
                        down vote













                        nrow() is simplest, but if you want to do it using data.table syntax:



                        dt[Country == 'France' & Age > 32, (.N)]





                        share|improve this answer























                          up vote
                          1
                          down vote










                          up vote
                          1
                          down vote









                          nrow() is simplest, but if you want to do it using data.table syntax:



                          dt[Country == 'France' & Age > 32, (.N)]





                          share|improve this answer












                          nrow() is simplest, but if you want to do it using data.table syntax:



                          dt[Country == 'France' & Age > 32, (.N)]






                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered Nov 21 at 23:03









                          neilfws

                          17.5k53648




                          17.5k53648















                              -

                              Popular posts from this blog

                              A CLEAN and SIMPLE way to add appendices to Table of Contents and bookmarks

                              Image
                              0 I found a lot of questions abount appendices and ToC. Many users want appendices to be grouped in an Appendix part, however some problems arise with ToC, hyperref, PDF viewer bookmarks, and so on. There are different solutions which require extra packages, command patching and other extra code, however none of them satisfies me. I almost found an easy way to accomplish a good result, where appendices are added to bookmarks in the right way and hyperref links point to the right page. However, the number of the "Appendix" part page is wrong (it's the number of appendix A). Is there any EASY way to fix that? This is a MWE: documentclass{book} usepackage[nottoc,notlot,notlof]{tocbibind} usepackage{hyperref} begin{document} frontmatter tableofcontents mainmatter part{First} chapter{...
                              Read more

                              Calculate evaluation metrics using cross_val_predict sklearn

                              Image
                              1 In the sklearn.model_selection.cross_val_predict page it is stated: Generate cross-validated estimates for each input data point. It is not appropriate to pass these predictions into an evaluation metric. Can someone explain what does it mean? If this gives estimate of Y (y prediction) for every Y (true Y), why can't I calculate metrics such as RMSE or coefficient of determination using these results? python scikit-learn cross-validation share | improve this question edited Nov 28 '18 at 17:52 desertnaut 20.3k 7 43 79 ...
                              Read more

                              Insert data from modal to MySQL (multiple modal on website)

                              Image
                              0 I have problem with inserting data to MySQL from modal. My modal: <a href="#" class="badge badge-pill badge-success">6 komentarzy</a> <a href="#" class="badge badge-pill badge-danger">brak komentarzy</a> <a data-toggle="modal" href="#add_desk_comm_{$desk_['desk_id']}" data-target="#add_desk_comm_{$desk_['desk_id']}" class="ediiit">(dodaj)</a> <div class="modal fade" id="add_desk_comm_{$desk_['desk_id']}" tabindex="-1" role="dialog" aria-labelledby="edit_printer" aria-hidden="true"> <div class="modal-dialog" role="document"> ...
                              Read more