[R] tidyverse: grouped summaries (with summerize)

[Rich Shepard]

On Tue, 14 Sep 2021, Eric Berger wrote:

> This code is not correct:
> disc_by_month %>%
>     group_by(year, month) %>%
>     summarize(disc_by_month, vol = mean(cfs, na.rm = TRUE))
> It should be:
> disc %>% group_by(year,month) %>% summarize(vol=mean(cfs,na.rm=TRUE)

Eric/Avi:

That makes no difference:
> disc_by_month
# A tibble: 590,940 × 6
# Groups:   year, month [66]
     year month   day  hour   min    cfs
    <int> <int> <int> <int> <int>  <dbl>
  1  2016     3     3    12     0 149000
  2  2016     3     3    12    10 150000
  3  2016     3     3    12    20 151000
  4  2016     3     3    12    30 156000
  5  2016     3     3    12    40 154000
  6  2016     3     3    12    50 150000
  7  2016     3     3    13     0 153000
  8  2016     3     3    13    10 156000
  9  2016     3     3    13    20 154000
10  2016     3     3    13    30 155000
# … with 590,930 more rows

I wondered if I need to group first by hour, then day, then year-month.
This, too, produces the same output:

disc %>%
     group_by(hour) %>%
     group_by(day) %>%
     group_by(year, month) %>%
     summarize(disc_by_month, vol = mean(cfs, na.rm = TRUE))

And disc shows the read dataframe.

I don't understand why the columns are not grouping.

Thanks,

Rich