Calculate new values by row












0















I'd like to create a new column (val_new) in which each value is multiplied by a value in another column (val2) by row. As I want to do this for several groups I'd prefer using dplyr, but how?



dat <- data.frame(group = rep(c("A", "B"), each = 3),
val1 = c(50, NA, NA, 40, NA, NA),
val2 = c(NA, 0.5, 0.3, NA, 0.8, 0.7))

> dat
group val1 val2
1 A 50 NA
2 A NA 0.5
3 A NA 0.3
4 B 40 NA
5 B NA 0.8
6 B NA 0.7

dat %>%
group_by(group) %>%
mutate(val_new = ifelse(!is.na(val1), val1, lag(val_new) * val2))

Error in mutate_impl(.data, dots) :
Evaluation error: object 'val_new' not found.


Desired result:



# A tibble: 6 x 4
# Groups: group [2]
group val1 val2 val_new
<fct> <dbl> <dbl> <dbl>
1 A 50 NA 50
2 A NA 0.5 25
3 A NA 0.3 7.5
4 B 40 NA 40
5 B NA 0.8 32
6 B NA 0.7 22.4









share|improve this question



























    0















    I'd like to create a new column (val_new) in which each value is multiplied by a value in another column (val2) by row. As I want to do this for several groups I'd prefer using dplyr, but how?



    dat <- data.frame(group = rep(c("A", "B"), each = 3),
    val1 = c(50, NA, NA, 40, NA, NA),
    val2 = c(NA, 0.5, 0.3, NA, 0.8, 0.7))

    > dat
    group val1 val2
    1 A 50 NA
    2 A NA 0.5
    3 A NA 0.3
    4 B 40 NA
    5 B NA 0.8
    6 B NA 0.7

    dat %>%
    group_by(group) %>%
    mutate(val_new = ifelse(!is.na(val1), val1, lag(val_new) * val2))

    Error in mutate_impl(.data, dots) :
    Evaluation error: object 'val_new' not found.


    Desired result:



    # A tibble: 6 x 4
    # Groups: group [2]
    group val1 val2 val_new
    <fct> <dbl> <dbl> <dbl>
    1 A 50 NA 50
    2 A NA 0.5 25
    3 A NA 0.3 7.5
    4 B 40 NA 40
    5 B NA 0.8 32
    6 B NA 0.7 22.4









    share|improve this question

























      0












      0








      0








      I'd like to create a new column (val_new) in which each value is multiplied by a value in another column (val2) by row. As I want to do this for several groups I'd prefer using dplyr, but how?



      dat <- data.frame(group = rep(c("A", "B"), each = 3),
      val1 = c(50, NA, NA, 40, NA, NA),
      val2 = c(NA, 0.5, 0.3, NA, 0.8, 0.7))

      > dat
      group val1 val2
      1 A 50 NA
      2 A NA 0.5
      3 A NA 0.3
      4 B 40 NA
      5 B NA 0.8
      6 B NA 0.7

      dat %>%
      group_by(group) %>%
      mutate(val_new = ifelse(!is.na(val1), val1, lag(val_new) * val2))

      Error in mutate_impl(.data, dots) :
      Evaluation error: object 'val_new' not found.


      Desired result:



      # A tibble: 6 x 4
      # Groups: group [2]
      group val1 val2 val_new
      <fct> <dbl> <dbl> <dbl>
      1 A 50 NA 50
      2 A NA 0.5 25
      3 A NA 0.3 7.5
      4 B 40 NA 40
      5 B NA 0.8 32
      6 B NA 0.7 22.4









      share|improve this question














      I'd like to create a new column (val_new) in which each value is multiplied by a value in another column (val2) by row. As I want to do this for several groups I'd prefer using dplyr, but how?



      dat <- data.frame(group = rep(c("A", "B"), each = 3),
      val1 = c(50, NA, NA, 40, NA, NA),
      val2 = c(NA, 0.5, 0.3, NA, 0.8, 0.7))

      > dat
      group val1 val2
      1 A 50 NA
      2 A NA 0.5
      3 A NA 0.3
      4 B 40 NA
      5 B NA 0.8
      6 B NA 0.7

      dat %>%
      group_by(group) %>%
      mutate(val_new = ifelse(!is.na(val1), val1, lag(val_new) * val2))

      Error in mutate_impl(.data, dots) :
      Evaluation error: object 'val_new' not found.


      Desired result:



      # A tibble: 6 x 4
      # Groups: group [2]
      group val1 val2 val_new
      <fct> <dbl> <dbl> <dbl>
      1 A 50 NA 50
      2 A NA 0.5 25
      3 A NA 0.3 7.5
      4 B 40 NA 40
      5 B NA 0.8 32
      6 B NA 0.7 22.4






      r dplyr






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      asked Nov 23 '18 at 10:10









      beetrootbeetroot

      6,63473060




      6,63473060
























          1 Answer
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          Try this:



          dat %>% 
          group_by(group) %>%
          mutate(val_new = cumprod(c(first(val1),val2[-1])))
          ## A tibble: 6 x 4
          ## Groups: group [2]
          # group val1 val2 val_new
          # <fct> <dbl> <dbl> <dbl>
          #1 A 50 NA 50
          #2 A NA 0.5 25
          #3 A NA 0.3 7.5
          #4 B 40 NA 40
          #5 B NA 0.8 32
          #6 B NA 0.7 22.4





          share|improve this answer























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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            2














            Try this:



            dat %>% 
            group_by(group) %>%
            mutate(val_new = cumprod(c(first(val1),val2[-1])))
            ## A tibble: 6 x 4
            ## Groups: group [2]
            # group val1 val2 val_new
            # <fct> <dbl> <dbl> <dbl>
            #1 A 50 NA 50
            #2 A NA 0.5 25
            #3 A NA 0.3 7.5
            #4 B 40 NA 40
            #5 B NA 0.8 32
            #6 B NA 0.7 22.4





            share|improve this answer




























              2














              Try this:



              dat %>% 
              group_by(group) %>%
              mutate(val_new = cumprod(c(first(val1),val2[-1])))
              ## A tibble: 6 x 4
              ## Groups: group [2]
              # group val1 val2 val_new
              # <fct> <dbl> <dbl> <dbl>
              #1 A 50 NA 50
              #2 A NA 0.5 25
              #3 A NA 0.3 7.5
              #4 B 40 NA 40
              #5 B NA 0.8 32
              #6 B NA 0.7 22.4





              share|improve this answer


























                2












                2








                2







                Try this:



                dat %>% 
                group_by(group) %>%
                mutate(val_new = cumprod(c(first(val1),val2[-1])))
                ## A tibble: 6 x 4
                ## Groups: group [2]
                # group val1 val2 val_new
                # <fct> <dbl> <dbl> <dbl>
                #1 A 50 NA 50
                #2 A NA 0.5 25
                #3 A NA 0.3 7.5
                #4 B 40 NA 40
                #5 B NA 0.8 32
                #6 B NA 0.7 22.4





                share|improve this answer













                Try this:



                dat %>% 
                group_by(group) %>%
                mutate(val_new = cumprod(c(first(val1),val2[-1])))
                ## A tibble: 6 x 4
                ## Groups: group [2]
                # group val1 val2 val_new
                # <fct> <dbl> <dbl> <dbl>
                #1 A 50 NA 50
                #2 A NA 0.5 25
                #3 A NA 0.3 7.5
                #4 B 40 NA 40
                #5 B NA 0.8 32
                #6 B NA 0.7 22.4






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 23 '18 at 10:47









                nicolanicola

                18.6k21836




                18.6k21836






























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