Change the values of rows conditionally in R-CodePudding

My data looks like this:

company_name <- c("A","A","A","A","B","B","B")
year <- c(1985, 1986, 1987, 1988, 1985, 1986, 1987)
value <- c(0, 1, 0, 0, 1, 0, 0)

df <- data.frame(company_name, year, value)

If the value is 1, I want to switch this row of value (value=1) with the next row (value=0). (group_by should be used for company_name) My output must be like this:

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

new_df <- data.frame(company_name, year, value)

CodePudding user response：

Here is one potential solution:

library(dplyr)

company_name <- c("A","A","A","A","B","B","B")
year <- c(1985, 1986, 1987, 1988, 1985, 1986, 1987)
value <- c(0, 1, 0, 0, 1, 0, 0)

df <- data.frame(company_name, year, value)

answer <- df %>%
  group_by(company_name) %>%
  mutate(value = ifelse(lag(value, default = 0) == 1, lag(value), 0))

value <- c(0, 0, 1, 0, 0, 1, 0)
new_df <- data.frame(company_name, year, value)

all_equal(answer, new_df)
#> [1] TRUE

^{Created on 2022-11-25 by the reprex package (v2.0.1)}

CodePudding user response：

Using dplyr::lag() and dplyr::lead() to test and replace values:

library(dplyr)

df %>%
group_by(company_name) %>%
  mutate(value = case_when(
    value == 1 ~ lead(value), 
    lag(value) == 1 ~ 1,
    TRUE ~ value
  ))

# A tibble: 7 × 3
# Groups:   company_name [2]
  company_name  year value
  <chr>        <dbl> <dbl>
1 A             1985     0
2 A             1986     0
3 A             1987     1
4 A             1988     0
5 B             1985     0
6 B             1986     1
7 B             1987     0