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How to obtain a position of last non-zero element



The 2019 Stack Overflow Developer Survey Results Are In
Unicorn Meta Zoo #1: Why another podcast?
Announcing the arrival of Valued Associate #679: Cesar Manara
The Ask Question Wizard is Live!
Data science time! April 2019 and salary with experienceHow to trim leading and trailing whitespace?How do I replace NA values with zeros in an R dataframe?data.table vs dplyr: can one do something well the other can't or does poorly?Calculate days since last event in REfficient way of taking the max date within groupsTurn off verbose messages when loading tidyverse using library() functionColumn name of last non-NA row per row; using tidyverse solution?Filtering data relative to first and last occurance of an eventdplyr approach to get the last row number with a positive valueA code to imput missing values with linear dependency



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16















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




























    16















    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
























      16












      16








      16


      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 yesterday









      jakesjakes

      431315




      431315






















          4 Answers
          4






          active

          oldest

          votes


















          17














          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
            yesterday






          • 3





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

            – jogo
            yesterday











          • @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
            yesterday


















          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























                Your Answer






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                4 Answers
                4






                active

                oldest

                votes








                4 Answers
                4






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes









                17














                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
                  yesterday






                • 3





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

                  – jogo
                  yesterday











                • @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
                  yesterday















                17














                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
                  yesterday






                • 3





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

                  – jogo
                  yesterday











                • @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
                  yesterday













                17












                17








                17







                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 yesterday









                mgiormentimgiormenti

                394111




                394111







                • 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
                  yesterday






                • 3





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

                  – jogo
                  yesterday











                • @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
                  yesterday












                • 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
                  yesterday






                • 3





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

                  – jogo
                  yesterday











                • @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
                  yesterday







                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
                yesterday





                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
                yesterday




                3




                3





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

                – jogo
                yesterday





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

                – jogo
                yesterday













                @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
                yesterday





                @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
                yesterday













                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 yesterday









                    Konrad RudolphKonrad Rudolph

                    404k1017921041




                    404k1017921041





















                        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 yesterday









                            RushabhRushabh

                            1,300221




                            1,300221





















                                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 yesterday









                                    Ronak ShahRonak Shah

                                    46.7k104269




                                    46.7k104269



























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