# [R] Selecting elements

PIKAL Petr petr@p|k@| @end|ng |rom prechez@@cz
Fri Aug 20 08:27:59 CEST 2021

```Hallo

I am confused, maybe others know what do you want but could you be more specific?

Let say you have such data
set.seed(123)
Var.1 = rep(LETTERS[1:4], 10)
Var.2 = sample(1:40, replace=FALSE)
data = data.frame(Var.1, Var.2)

What should be the desired outcome?

You can sort
data <- data[order(data\$Var.2, decreasing=TRUE), ]
and split the data
> split(data\$Var.2, data\$Var.1)
\$A
[1] 38 35 32 31 30 22 11  8  2  1

\$B
[1] 39 28 25 23 16 15  7  6  5  4

\$C
[1] 40 36 29 26 21 19 18 14 10  9

\$D
[1] 37 34 33 27 24 20 17 13 12  3

T inspect highest values. But here I am lost. As C is first and fourth biggest value, you follow third option and select 3 highest A, 3B 2C and 2D?

Or I do not understand at all what you really want to achieve.

Cheers
Petr

> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of Silvano Cesar da
> Costa
> Sent: Thursday, August 19, 2021 10:40 PM
> To: r-help using r-project.org
> Subject: [R] Selecting elements
>
> Hi,
>
> I need to select 15 elements, always considering the highest values
> (descending order) but obeying the following configuration:
>
> 3A - 4B - 0C - 3D or
> 2A - 5B - 0C - 3D or
> 3A - 3B - 2C - 2D
>
> If I have, for example, 5 A elements as the highest values, I can only choose
> (first and third choice) or 2 (second choice) elements.
>
> how to make this selection?
>
>
> library(dplyr)
>
> Var.1 = rep(LETTERS[1:4], 10)
> Var.2 = sample(1:40, replace=FALSE)
>
> data = data.frame(Var.1, Var.2)
> (data = data[order(data\$Var.2, decreasing=TRUE), ])
>
> Elements = data %>%
>   arrange(desc(Var.2))
>
> Thanks,
>
> Prof. Dr. Silvano Cesar da Costa
> Centro de Ciências Exatas
> Departamento de Estatística
>
> Fone: (43) 3371-4346
>
> 	[[alternative HTML version deleted]]
>
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