I would like to filter to remove all rows before a particular value in a specific column. For example, in the data frame below, I would like to remove all rows before "1" that appears in column x, for as much as "1" occurs. Please note that the value of "1" repeats many times and I want to remove the "NA" rows before the "1" in column x, regarding column a. Thanks
a b x
1 1 NA
1 2 NA
1 3 1
1 4 0
1 5 0
1 6 NA
1 7 NA
2 1 NA
2 2 NA
2 3 1
2 4 NA
2 5 0
2 6 0
2 7 NA
3 1 NA
3 2 NA
3 3 NA
3 4 NA
3 5 1
3 6 0
3 7 NA
the desired output would be like this:
a b x
1 3 1
1 4 0
1 5 0
1 6 NA
1 7 NA
2 3 1
2 4 NA
2 5 0
2 6 0
2 7 NA
3 5 1
3 6 0
3 7 NA
CodePudding user response:
Does this solve your problem?
library(tidyverse)
dat <- read.table(text = "a b x
1 1 NA
1 2 NA
1 3 1
1 4 0
1 5 0
1 6 NA
1 7 NA
2 1 NA
2 2 NA
2 3 1
2 4 NA
2 5 0
2 6 0
2 7 NA
3 1 NA
3 2 NA
3 3 NA
3 4 NA
3 5 1
3 6 0
3 7 NA", header = TRUE)
dat %>%
group_by(a) %>%
filter(cummax(!is.na(x)) == 1)
#> # A tibble: 13 × 3
#> # Groups: a [3]
#> a b x
#> <int> <int> <int>
#> 1 1 3 1
#> 2 1 4 0
#> 3 1 5 0
#> 4 1 6 NA
#> 5 1 7 NA
#> 6 2 3 1
#> 7 2 4 NA
#> 8 2 5 0
#> 9 2 6 0
#> 10 2 7 NA
#> 11 3 5 1
#> 12 3 6 0
#> 13 3 7 NA
Created on 2021-12-07 by the reprex package (v2.0.1)