R help - Sep 2021 - tidyverse: grouped summaries (with summarize) [RESOLVED]

On Mon, 13 Sep 2021, Avi Gross via R-help wrote:
> As Eric has pointed out, perhaps Rich is not thinking pipelined.
Summarize() takes a first argument as:
> 	summarise(.data=whatever, ...)
>
> But in a pipeline, you OMIT the first argument and let the pipeline supply
an argument silently.
Avi,

Thank you. I read your message carefully and re-read the example on the
bottom of page 60 and top of page 61. Then changed the command to:
disc_by_month = disc %>%
     group_by(year, month) %>%
     summarize(vol = mean(cfs, na.rm = TRUE))

And, the script now returns what I need:
> disc_by_month
# A tibble: 66 ? 3
# Groups:   year [7]
     year month     vol
    <int> <int>   <dbl>
  1  2016     3 221840.
  2  2016     4 288589.
  3  2016     5 255164.
  4  2016     6 205371.
  5  2016     7 167252.
  6  2016     8 140465.
  7  2016     9  97779.
  8  2016    10 135482.
  9  2016    11 166808.
10  2016    12 165787.

I missed the beginning of the command where the resulting dataframe needs to
be named first.

This clarifies my understanding and I appreciate your and Eric's help.

Regards,

Rich

Just FYI, Rich, the way the idiom with pipeline works does allow but not require
the method you used:

Yours was
  RESULT <-
    DATAFRAME %>%
    FN1(args) %>%
    ...
    FNn(args)
    
But equally valid are forms that assign the result at the end:

    DATAFRAME %>%
    FN1(args) %>%
    ...
    FNn(args) -> RESULT

Or that supply the first argument to just the first function:

    FN1(DATAFRAME, args) %>%
    ...
    FNn(args) -> RESULT

And if you read some tutorials, there are many other things you can do including
variants on the pipe symbol to do other things but also how to put the variable
returned into a different part (not the first position) of the argument that
follows and lots more. Some people spend most of the programming time relatively
purely in the tidyverse functions without looking much at base R.

I am not saying that is a good thing.


-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of Rich Shepard
Sent: Monday, September 13, 2021 7:04 PM
To: r-help at r-project.org
Subject: Re: [R] tidyverse: grouped summaries (with summarize) [RESOLVED]

On Mon, 13 Sep 2021, Avi Gross via R-help wrote:
> As Eric has pointed out, perhaps Rich is not thinking pipelined.
Summarize() takes a first argument as:
> 	summarise(.data=whatever, ...)
>
> But in a pipeline, you OMIT the first argument and let the pipeline supply
an argument silently.
Avi,

Thank you. I read your message carefully and re-read the example on the bottom
of page 60 and top of page 61. Then changed the command to:
disc_by_month = disc %>%
     group_by(year, month) %>%
     summarize(vol = mean(cfs, na.rm = TRUE))

And, the script now returns what I need:
> disc_by_month
# A tibble: 66 ? 3
# Groups:   year [7]
     year month     vol
    <int> <int>   <dbl>
  1  2016     3 221840.
  2  2016     4 288589.
  3  2016     5 255164.
  4  2016     6 205371.
  5  2016     7 167252.
  6  2016     8 140465.
  7  2016     9  97779.
  8  2016    10 135482.
  9  2016    11 166808.
10  2016    12 165787.

I missed the beginning of the command where the resulting dataframe needs to be
named first.

This clarifies my understanding and I appreciate your and Eric's help.

Regards,

Rich

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