How to rank the data by a variable value and create a order variable?

[Visiting]

How to rank variable and create a new variable to display the order? for example, following data frame, want to sort the data by var1 and generate a new variable for the order, let ties have the same order number. Thank you!

input<-("var1 var2
1 2
3 4
1 3
2 5
2 6
4 5
6 7")

mydata<- read.table(textConnection(input),header=T)

[mfherman]

Here are a couple approaches using functions from dplyr depending on how you want the ranking to be numbered

library(tidyverse)

input <- ("var1 var2
1 2
3 4
1 3
2 5
2 6
4 5
6 7")

mydata <- read.table(textConnection(input), header = T)

# ties get lower number rank
mydata %>%
  mutate(rank_order = min_rank(var1)) %>%
  arrange(rank_order)
#>   var1 var2 rank_order
#> 1    1    2          1
#> 2    1    3          1
#> 3    2    5          3
#> 4    2    6          3
#> 5    3    4          5
#> 6    4    5          6
#> 7    6    7          7

# same as above but no gaps between ranks
mydata %>%
  mutate(rank_order = dense_rank(var1)) %>%
  arrange(rank_order)
#>   var1 var2 rank_order
#> 1    1    2          1
#> 2    1    3          1
#> 3    2    5          2
#> 4    2    6          2
#> 5    3    4          3
#> 6    4    5          4
#> 7    6    7          5

^{Created on 2018-11-20 by the reprex package (v0.2.1)}

[Visiting]

Thank you! one more question: if there are missing value in the rank variable and want to let missing value in the last, how to do that?

[mfherman]

Glad to help!

If there is NA in the ranking variable, you will get NA in the rank order column. Is that how you want NAs to be handled?

library(tidyverse)

# with NA
mydata2 <- tribble(
  ~var1, ~var2,
  1, 2,
  3, 4,
  NA, 3,
  2, 5,
  2, 6,
  4, 5,
  6, 7
)

# ties get lower number rank
mydata2 %>%
  mutate(rank_order = min_rank(var1)) %>%
  arrange(rank_order)
#> # A tibble: 7 x 3
#>    var1  var2 rank_order
#>   <dbl> <dbl>      <int>
#> 1     1     2          1
#> 2     2     5          2
#> 3     2     6          2
#> 4     3     4          4
#> 5     4     5          5
#> 6     6     7          6
#> 7    NA     3         NA

^{Created on 2018-11-20 by the reprex package (v0.2.1)}

[Visiting]

Thank you so much!!!!!!!!!!!!!!!!!!!!!!!!!!1