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How to obtain a position of last non-zero element



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 23, 2019 at 23:30UTC (7:30pm US/Eastern)
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18















I've got a binary variable representing if event happened or not:



event <- c(0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0)


I need to obtain a variable that would indicate the time when the last event happened. The expected output would be:



last_event <- c(0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 13, 13, 13, 13)


How can I obtain that with base R, tidyverse or any other way?










share|improve this question




























    18















    I've got a binary variable representing if event happened or not:



    event <- c(0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0)


    I need to obtain a variable that would indicate the time when the last event happened. The expected output would be:



    last_event <- c(0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 13, 13, 13, 13)


    How can I obtain that with base R, tidyverse or any other way?










    share|improve this question
























      18












      18








      18


      1






      I've got a binary variable representing if event happened or not:



      event <- c(0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0)


      I need to obtain a variable that would indicate the time when the last event happened. The expected output would be:



      last_event <- c(0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 13, 13, 13, 13)


      How can I obtain that with base R, tidyverse or any other way?










      share|improve this question














      I've got a binary variable representing if event happened or not:



      event <- c(0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0)


      I need to obtain a variable that would indicate the time when the last event happened. The expected output would be:



      last_event <- c(0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 13, 13, 13, 13)


      How can I obtain that with base R, tidyverse or any other way?







      r tidyverse base






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Apr 11 at 14:08









      jakesjakes

      481315




      481315






















          4 Answers
          4






          active

          oldest

          votes


















          18














          Taking advantage of the fact that you have a binary vector, the following gives your desired output:



          cummax(seq_along(event) * event)





          share|improve this answer


















          • 6





            Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

            – Konrad Rudolph
            Apr 11 at 14:27






          • 3





            or without multiplication cummax(ifelse(event, seq_along(event), 0))

            – jogo
            Apr 11 at 14:27











          • @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

            – Konrad Rudolph
            Apr 11 at 14:28


















          8














          Whenever you need to fill repetitions with a value, think run-length encoding.



          In this case, you can determine the run lengths and then repeat the indices of count == 0 an according number of times:



          lengths = rle(event == 0)$lengths
          nonzeros = which(event != 0)
          runs = c(0, rep(nonzeros, each = 2))
          result = rep(runs, lengths)


          Alternative, substitute the runs in the RLE and then inverse it:



          rle = rle(event == 0)
          nonzeros = which(event != 0)
          rle$values = c(0, rep(nonzeros, each = 2))
          result = inverse.rle(rle)





          share|improve this answer






























            1














            You can also do somthing like this-



            > zero.locf <- function(x) 
            v <- x!=0
            c(0, x[v])[cumsum(v)+1]


            > zero.locf(1:length(event)*event)

            [1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





            share|improve this answer






























              1














              Another option is to find the index where event == 1 and repeat it based on length.



              rep(c(0, which(event == 1)), tapply(event, cumsum(event == 1), length))
              #[1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





              share|improve this answer























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                4 Answers
                4






                active

                oldest

                votes








                4 Answers
                4






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes









                18














                Taking advantage of the fact that you have a binary vector, the following gives your desired output:



                cummax(seq_along(event) * event)





                share|improve this answer


















                • 6





                  Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                  – Konrad Rudolph
                  Apr 11 at 14:27






                • 3





                  or without multiplication cummax(ifelse(event, seq_along(event), 0))

                  – jogo
                  Apr 11 at 14:27











                • @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                  – Konrad Rudolph
                  Apr 11 at 14:28















                18














                Taking advantage of the fact that you have a binary vector, the following gives your desired output:



                cummax(seq_along(event) * event)





                share|improve this answer


















                • 6





                  Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                  – Konrad Rudolph
                  Apr 11 at 14:27






                • 3





                  or without multiplication cummax(ifelse(event, seq_along(event), 0))

                  – jogo
                  Apr 11 at 14:27











                • @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                  – Konrad Rudolph
                  Apr 11 at 14:28













                18












                18








                18







                Taking advantage of the fact that you have a binary vector, the following gives your desired output:



                cummax(seq_along(event) * event)





                share|improve this answer













                Taking advantage of the fact that you have a binary vector, the following gives your desired output:



                cummax(seq_along(event) * event)






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Apr 11 at 14:24









                mgiormentimgiormenti

                444211




                444211







                • 6





                  Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                  – Konrad Rudolph
                  Apr 11 at 14:27






                • 3





                  or without multiplication cummax(ifelse(event, seq_along(event), 0))

                  – jogo
                  Apr 11 at 14:27











                • @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                  – Konrad Rudolph
                  Apr 11 at 14:28












                • 6





                  Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                  – Konrad Rudolph
                  Apr 11 at 14:27






                • 3





                  or without multiplication cummax(ifelse(event, seq_along(event), 0))

                  – jogo
                  Apr 11 at 14:27











                • @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                  – Konrad Rudolph
                  Apr 11 at 14:28







                6




                6





                Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                – Konrad Rudolph
                Apr 11 at 14:27





                Yes! So much more elegant than my solution. I was thinking about cumulative sums but I didn’t think of multiplying the indices by the binary vector.

                – Konrad Rudolph
                Apr 11 at 14:27




                3




                3





                or without multiplication cummax(ifelse(event, seq_along(event), 0))

                – jogo
                Apr 11 at 14:27





                or without multiplication cummax(ifelse(event, seq_along(event), 0))

                – jogo
                Apr 11 at 14:27













                @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                – Konrad Rudolph
                Apr 11 at 14:28





                @jogo That solution makes sense if the type of event is logical. It does work even for a numeric vector due to R’s implicit conversions but … eh.

                – Konrad Rudolph
                Apr 11 at 14:28













                8














                Whenever you need to fill repetitions with a value, think run-length encoding.



                In this case, you can determine the run lengths and then repeat the indices of count == 0 an according number of times:



                lengths = rle(event == 0)$lengths
                nonzeros = which(event != 0)
                runs = c(0, rep(nonzeros, each = 2))
                result = rep(runs, lengths)


                Alternative, substitute the runs in the RLE and then inverse it:



                rle = rle(event == 0)
                nonzeros = which(event != 0)
                rle$values = c(0, rep(nonzeros, each = 2))
                result = inverse.rle(rle)





                share|improve this answer



























                  8














                  Whenever you need to fill repetitions with a value, think run-length encoding.



                  In this case, you can determine the run lengths and then repeat the indices of count == 0 an according number of times:



                  lengths = rle(event == 0)$lengths
                  nonzeros = which(event != 0)
                  runs = c(0, rep(nonzeros, each = 2))
                  result = rep(runs, lengths)


                  Alternative, substitute the runs in the RLE and then inverse it:



                  rle = rle(event == 0)
                  nonzeros = which(event != 0)
                  rle$values = c(0, rep(nonzeros, each = 2))
                  result = inverse.rle(rle)





                  share|improve this answer

























                    8












                    8








                    8







                    Whenever you need to fill repetitions with a value, think run-length encoding.



                    In this case, you can determine the run lengths and then repeat the indices of count == 0 an according number of times:



                    lengths = rle(event == 0)$lengths
                    nonzeros = which(event != 0)
                    runs = c(0, rep(nonzeros, each = 2))
                    result = rep(runs, lengths)


                    Alternative, substitute the runs in the RLE and then inverse it:



                    rle = rle(event == 0)
                    nonzeros = which(event != 0)
                    rle$values = c(0, rep(nonzeros, each = 2))
                    result = inverse.rle(rle)





                    share|improve this answer













                    Whenever you need to fill repetitions with a value, think run-length encoding.



                    In this case, you can determine the run lengths and then repeat the indices of count == 0 an according number of times:



                    lengths = rle(event == 0)$lengths
                    nonzeros = which(event != 0)
                    runs = c(0, rep(nonzeros, each = 2))
                    result = rep(runs, lengths)


                    Alternative, substitute the runs in the RLE and then inverse it:



                    rle = rle(event == 0)
                    nonzeros = which(event != 0)
                    rle$values = c(0, rep(nonzeros, each = 2))
                    result = inverse.rle(rle)






                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered Apr 11 at 14:23









                    Konrad RudolphKonrad Rudolph

                    404k1017951041




                    404k1017951041





















                        1














                        You can also do somthing like this-



                        > zero.locf <- function(x) 
                        v <- x!=0
                        c(0, x[v])[cumsum(v)+1]


                        > zero.locf(1:length(event)*event)

                        [1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                        share|improve this answer



























                          1














                          You can also do somthing like this-



                          > zero.locf <- function(x) 
                          v <- x!=0
                          c(0, x[v])[cumsum(v)+1]


                          > zero.locf(1:length(event)*event)

                          [1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                          share|improve this answer

























                            1












                            1








                            1







                            You can also do somthing like this-



                            > zero.locf <- function(x) 
                            v <- x!=0
                            c(0, x[v])[cumsum(v)+1]


                            > zero.locf(1:length(event)*event)

                            [1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                            share|improve this answer













                            You can also do somthing like this-



                            > zero.locf <- function(x) 
                            v <- x!=0
                            c(0, x[v])[cumsum(v)+1]


                            > zero.locf(1:length(event)*event)

                            [1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13






                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered Apr 11 at 14:30









                            RushabhRushabh

                            1,332222




                            1,332222





















                                1














                                Another option is to find the index where event == 1 and repeat it based on length.



                                rep(c(0, which(event == 1)), tapply(event, cumsum(event == 1), length))
                                #[1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                                share|improve this answer



























                                  1














                                  Another option is to find the index where event == 1 and repeat it based on length.



                                  rep(c(0, which(event == 1)), tapply(event, cumsum(event == 1), length))
                                  #[1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                                  share|improve this answer

























                                    1












                                    1








                                    1







                                    Another option is to find the index where event == 1 and repeat it based on length.



                                    rep(c(0, which(event == 1)), tapply(event, cumsum(event == 1), length))
                                    #[1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13





                                    share|improve this answer













                                    Another option is to find the index where event == 1 and repeat it based on length.



                                    rep(c(0, which(event == 1)), tapply(event, cumsum(event == 1), length))
                                    #[1] 0 0 0 0 5 5 5 5 5 5 5 5 13 13 13 13






                                    share|improve this answer












                                    share|improve this answer



                                    share|improve this answer










                                    answered Apr 11 at 14:31









                                    Ronak ShahRonak Shah

                                    48.5k104369




                                    48.5k104369



























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