How to assign a "reseting" group number by the second grouping variable in R?-CodePudding

My data looks like this:

Measurement	Compound	Measure
1	A	111
1	A	222
1	B	333
1	B	444
2	C	555
2	C	666
2	D	777
2	D	888

And I'm trying to assign a "reseting" group number based on Compound:

Measurement	Compound	Measure	Compound_order
1	A	111	1
1	A	222	1
1	B	333	2
1	B	444	2
2	C	555	1
2	C	666	1
2	D	777	2
2	D	888	2

Didn't come up with the solution on dplyr group_by.

DATA

dat <- data.frame(
  Measurement = c(1, 1, 1, 1, 2, 2, 2, 2),
  Compound = c("A", "A", "B", "B", "C", "C", "D", 'D'),
  Measure = 111 * 1:8
)

CodePudding user response：

You can do the following.

library(dplyr)

dat2 <- dat %>%
  group_by(Measurement) %>%
  mutate(Compound_order = as.integer(factor(Compound,
                                            levels = unique(Compound)))) %>%
  ungroup()

dat2
# # A tibble: 8 x 4
#   Measurement Compound Measure Compound_order
#         <dbl> <chr>      <dbl>          <int>
# 1           1 A            111              1
# 2           1 A            222              1
# 3           1 B            333              2
# 4           1 B            444              2
# 5           2 C            555              1
# 6           2 C            666              1
# 7           2 D            777              2
# 8           2 D            888              2

DATA

dat <- data.frame(
  Measurement = c(1, 1, 1, 1, 2, 2, 2, 2),
  Compound = c("A", "A", "B", "B", "C", "C", "D", 'D'),
  Measure = 111 * 1:8
)

CodePudding user response：

data.tablesolution

library(data.table)
setDT(dat)[, Compound_order := rleid(Compound), by = .(Measurement)]
#    Measurement Compound Measure Compound_order
# 1:           1        A     111              1
# 2:           1        A     222              1
# 3:           1        B     333              2
# 4:           1        B     444              2
# 5:           2        C     555              1
# 6:           2        C     666              1
# 7:           2        D     777              2
# 8:           2        D     888              2

CodePudding user response：

Like this:

library(tidyverse)
dat <- data.frame(
  measument = c(1,1,2,2),
  compount = c(letters[1:4])
)

dat %>% group_by(measument) %>% 
  mutate(compount_order = 1:n())
#> # A tibble: 4 x 3
#> # Groups:   measument [2]
#>   measument compount compount_order
#>       <dbl> <chr>             <int>
#> 1         1 a                     1
#> 2         1 b                     2
#> 3         2 c                     1
#> 4         2 d                     2

^{Created on 2021-11-05 by the reprex package (v2.0.0)}