[R] Find tibble row with maximum recorded value

[Rui Barradas]

Hello,

You're right, I carelessly coded this.

which.max returns the index to the first maximum of a vector, while the 
comparison of a vector with its max() returns an index to all vector 
elements.

Às 23:27 de 03/12/21, Bert Gunter escreveu:
> Perhaps you meant to point this out, but the cfs[which.max(cfs)] and
> cfs == ... are not the same:
> 
>> x <- rep(1:2,3)
>> x
> [1] 1 2 1 2 1 2
>> x[which.max(x)]
> [1] 2
>> x[x==max(x)]
> [1] 2 2 2
> 
> So maybe your point is: which does the OP want (in case there are
> repeated maxes)? I suspect the == forms, but ...?
> 
> Bert Gunter
> 
> On Fri, Dec 3, 2021 at 2:56 PM Rui Barradas <ruipbarradas using sapo.pt> wrote:
>>
>> Hello,
>>
>> Inline.
>>
>> Às 22:08 de 03/12/21, Rich Shepard escreveu:
>>> On Fri, 3 Dec 2021, Rich Shepard wrote:
>>>
>>>> I find solutions when the data_frame is grouped, but none when it's not.
>>>
>>> Thanks, Bert. ?which.max confirmed that's all I need to find the maximum
>>> value.
>>>
>>> Now I need to read more than ?filter to learn why I'm not getting the
>>> relevant row with:
>>>> which.max(pdx_disc$cfs)
>>> [1] 8054
>>
>> This is the *index* for which cfs is the first maximum, not the maximum
>> value itself.
>>
>>>
>>>> filter(pdx_disc, cfs == 8054)
>>
>> Therefore, you probably want any of

Should be "one of", not "any of"

Rui Barradas

>>
>>
>> filter(pdx_disc, cfs == cfs[8054])
>>
>> filter(pdx_disc, cfs == cfs[which.max(cfs)])
>>
>> filter(pdx_disc, cfs == max(cfs))    # I find this one better, simpler
>>
>>
>> Hope this helps,
>>
>> Rui Barradas
>>
>>
>>> # A tibble: 0 × 9
>>> # … with 9 variables: site_nbr <chr>, year <int>, mon <int>, day <int>,
>>> #   hr <dbl>, min <dbl>, tz <chr>, cfs <dbl>, sampdt <dttm>
>>>
>>> Regards,
>>>
>>> Rich
>>>
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>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.