I am a new user to R and do not understand how the syntax works. I know what I need to do, but do not know how to write it. I have the following dataframe:

```
tibble::tribble(~Time.x, ~Site.ID, ~Vol..mL..x, ~Soil.Type.x,
~Radius.x, 0L, "H1", 60L, "Sand", 5L, 30L, "H1", 60L, "Sand",
5L, 60L, "H1", 60L, "Sand", 5L, 90L, "H1", 60L, "Sand", 5L,
120L, "H1", 60L, "Sand", 5L, 150L, "H1", 60L, "Sand", 5L,
180L, "H1", 60L, "Sand", 5L, 210L, "H1", 60L, "Sand", 5L,
240L, "H1", 60L, "Sand", 5L, 270L, "H1", 60L, "Sand", 5L,
300L, "H1", 60L, "Sand", 5L, 0L, "H2", 60L, "Sand", 5L, 30L,
"H2", 60L, "Sand", 5L, 60L, "H2", 60L, "Sand", 5L, 90L, "H2",
60L, "Sand", 5L, 120L, "H2", 60L, "Sand", 5L, 150L, "H2",
60L, "Sand", 5L, 180L, "H2", 60L, "Sand", 5L, 210L, "H2",
60L, "Sand", 5L, 240L, "H2", 60L, "Sand", 5L, 270L, "H2",
60L, "Sand", 5L, 300L, "H2", 60L, "Sand", 5L, 330L, "H2",
60L, "Sand", 5L, 360L, "H2", 60L, "Sand", 5L)
#> # A tibble: 24 x 5
#> Time.x Site.ID Vol..mL..x Soil.Type.x Radius.x
#> <int> <chr> <int> <chr> <int>
#> 1 0 H1 60 Sand 5
#> 2 30 H1 60 Sand 5
#> 3 60 H1 60 Sand 5
#> 4 90 H1 60 Sand 5
#> 5 120 H1 60 Sand 5
#> 6 150 H1 60 Sand 5
#> 7 180 H1 60 Sand 5
#> 8 210 H1 60 Sand 5
#> 9 240 H1 60 Sand 5
#> 10 270 H1 60 Sand 5
#> # ... with 14 more rows
```

I would like to count the number of rows where Time.x = 0 to the row above when Time.x = 0 again. So for the first go through it would spit out 11 rows and for the second go through it would spit out 13. I have a much larger data frame with a ton more Site.ID's, so I am not sure if I need a loop or how to format this. I would assume to use nrow, but I do not know what to do afterwards.

Cheers!