which.max(dat$cfs), I presume.
see ?which.max
(as usual, true tidyverse questions belong on RStudio's help site, not here).
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Fri, Dec 3, 2021 at 12:56 PM Rich Shepard <rshep...@appl-ecosys.com> wrote:
>
> I find solutions when the data_frame is grouped, but none when it's not.
>
> The data:
> # A tibble: 813,693 × 9
> site_nbr year mon day hr min tz cfs sampdt
> <chr> <int> <int> <int> <dbl> <dbl> <chr> <dbl> <dttm>
> 1 14211720 1988 10 1 0 10 PDT 16800 1988-10-01 00:10:00
> 2 14211720 1988 10 1 0 20 PDT 16800 1988-10-01 00:20:00
> 3 14211720 1988 10 1 0 30 PDT 17300 1988-10-01 00:30:00
> 4 14211720 1988 10 1 0 40 PDT 18200 1988-10-01 00:40:00
> 5 14211720 1988 10 1 0 50 PDT 18100 1988-10-01 00:50:00
> 6 14211720 1988 10 1 1 0 PDT 18400 1988-10-01 01:00:00
> 7 14211720 1988 10 1 1 10 PDT 18700 1988-10-01 01:10:00
> 8 14211720 1988 10 1 1 20 PDT 19200 1988-10-01 01:20:00
> 9 14211720 1988 10 1 1 30 PDT 19200 1988-10-01 01:30:00
> 10 14211720 1988 10 1 1 40 PDT 18900 1988-10-01 01:40:00
> # … with 813,683 more rows
>
> The script:
> library(tidyverse)
>
> max_pdx_disc <- pdx_disc %>%
> summarize(max_cfs = max(cfs), max_cfs_sampdt = cfs(which.max(cfs)))
>
> The error:
> > source('../scripts/filter_by_column_max.r')
> Error: Problem with `summarise()` column `max_cfs_sampdt`.
> `max_cfs_sampdt = sampt(which.max(cfs))`.
> could not find function "sampt"
> > Run `rlang::last_error()` to see where the error occurred.
>
> I looked at the the last_error and the traceback without understanding how
> to filter the row with the maximum cfs value.
>
> What do I read to learn how to return this row?
>
> TIA,
>
> Rich
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
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