[R] Selecting elements
PIKAL Petr
petr@p|k@| @end|ng |rom prechez@@cz
Tue Aug 24 11:10:54 CEST 2021
Hi.
Now it is understandable. However the solution is not clear for me.
table(Order$Var.1[1:10])
A B C D
4 1 2 3
should give you a hint which scheme could be acceptable, but how to do it programmatically I do not know.
maybe to start with lower value in the table call and gradually increse it to check which scheme starts to be the chosen one
> table(data.o$Var.1[1]) # scheme 2 is out
C
1
...
> table(data.o$Var.1[1:5]) #scheme 3
A B C D
1 1 2 1
> table(data.o$Var.1[1:6]) #scheme 3
A B C D
2 1 2 1
> table(data.o$Var.1[1:7]) # scheme1
A B C D
2 1 2 2
> table(data.o$Var.1[1:8]) # no such scheme, so scheme 1 is chosen one
A B C D
2 1 2 3
#Now you need to select values based on scheme 1.
# 3A - 3B - 2C - 2D
sss <- split(Order, Order$Var.1)
selection <- c(3,3,2,2)
result <- vector("list", 4)
#I would use loop
for(i in 1:4) {
result[[i]] <- sss[[i]][1:selection[i],]
}
Maybe someone come with other ingenious solution.
Cheers
Petr
From: Silvano Cesar da Costa <silvano using uel.br>
Sent: Monday, August 23, 2021 7:54 PM
To: PIKAL Petr <petr.pikal using precheza.cz>
Cc: r-help using r-project.org
Subject: Re: [R] Selecting elements
Hi,
I apologize for the confusion. I will try to be clearer in my explanation. I believe that with the R script it becomes clearer.
I have 4 variables with 10 repetitions and each one receives a value, randomly.
I order the dataset from largest to smallest value. I have to select 10 elements in
descending order of values, according to one of three schemes:
# 3A - 3B - 2C - 2D
# 2A - 5B - 0C - 3D
# 3A - 4B - 2C - 1D
If the first 3 elements (out of the 10 to be selected) are of the letter D, automatically
the adopted scheme will be the second. So, I have to (following) choose 2A, 5B and 0C.
How to make the selection automatically?
I created two selection examples, with different schemes:
set.seed(123)
Var.1 = rep(LETTERS[1:4], 10)
Var.2 = sample(1:40, replace=FALSE)
data = data.frame(Var.1, Var.2)
(Order = data[order(data$Var.2, decreasing=TRUE), ])
# I must select the 10 highest values (),
# but which follow a certain scheme:
#
# 3A - 3B - 2C - 2D or
# 2A - 5B - 0C - 3D or
# 3A - 4B - 2C - 1D
#
# In this case, I started with the highest value that refers to the letter C.
# Next comes only 1 of the letters B, A and D. All are selected once.
# The fifth observation is the letter C, completing 2 C values. In this case,
# following the 3 adopted schemes, note that the second scheme has 0C,
# so this scheme is out.
# Therefore, it can be the first scheme (3A - 3B - 2C - 2D) or the
# third scheme (3A - 4B - 2C - 1D).
# The next letter to be completed is the D (fourth and seventh elements),
# among the 10 elements being selected. Therefore, the scheme adopted is the
# first one (3A - 3B - 2C - 2D).
# Therefore, it is necessary to select 2 values with the letter B and 1 value
# with the letter A.
#
# Manual Selection -
# The end result is:
(Selected.data = Order[c(1,2,3,4,5,6,7,9,13,16), ])
# Scheme: 3A - 3B - 2C - 2D
sort(Selected.data$Var.1)
#------------------
# Second example: -
#------------------
set.seed(4)
Var.1 = rep(LETTERS[1:4], 10)
Var.2 = sample(1:40, replace=FALSE)
data = data.frame(Var.1, Var.2)
(Order = data[order(data$Var.2, decreasing=TRUE), ])
# The end result is:
(Selected.data.2 = Order[c(1,2,3,4,5,6,7,8,9,11), ])
# Scheme: 3A - 4B - 2C - 1D
sort(Selected.data.2$Var.1)
How to make the selection of the 10 elements automatically?
Thank you very much.
Prof. Dr. Silvano Cesar da Costa
Universidade Estadual de Londrina
Centro de Ciências Exatas
Departamento de Estatística
Fone: (43) 3371-4346
Em seg., 23 de ago. de 2021 às 05:05, PIKAL Petr <mailto:petr.pikal using precheza.cz> escreveu:
Hi
Only I got your HTML formated mail, rest of the world got complete mess. Do not use HTML formating.
As I got it right I wonder why in your second example you did not follow
3A - 3B - 2C - 2D
as D were positioned 1st and 4th.
I hope that you could use something like
sss <- split(data$Var.2, data$Var.1)
lapply(sss, cumsum)
$A
[1] 38 73 105 136 166 188 199 207 209 210
$B
[1] 39 67 92 115 131 146 153 159 164 168
$C
[1] 40 76 105 131 152 171 189 203 213 222
$D
[1] 37 71 104 131 155 175 192 205 217 220
Now you need to evaluate this result according to your sets. Here the highest value (76) is in C so the set with 2C is the one you should choose and select you value according to this set.
With
> set.seed(666)
> Var.1 = rep(LETTERS[1:4], 10)
> Var.2 = sample(1:40, replace=FALSE)
> data = data.frame(Var.1, Var.2)
> data <- data[order(data$Var.2, decreasing=TRUE), ]
> sss <- split(data$Var.2, data$Var.1)
> lapply(sss, cumsum)
$A
[1] 36 70 102 133 163 182 200 207 212 213
$B
[1] 35 57 78 95 108 120 131 140 148 150
$C
[1] 40 73 102 130 156 180 196 211 221 225
$D
[1] 39 77 114 141 166 189 209 223 229 232
Highest value is in D so either 3A - 3B - 2C - 2D or 3A - 3B - 2C - 2D should be appropriate. And here I am again lost as both sets are same. Maybe you need to reconsider your statements.
Cheers
Petr
From: Silvano Cesar da Costa <mailto:silvano using uel.br>
Sent: Friday, August 20, 2021 9:28 PM
To: PIKAL Petr <mailto:petr.pikal using precheza.cz>
Cc: mailto:r-help using r-project.org
Subject: Re: [R] Selecting elements
Hi, thanks you for the answer.
Sorry English is not my native language.
But you got it right.
> As C is first and fourth biggest value, you follow third option and select 3 highest A, 3B 2C and 2D?
I must select the 10 (not 15) highest values, but which follow a certain order:
3A - 3B - 2C - 2D or
2A - 5B - 0C - 3D or
3A - 3B - 2C - 2D
I'll put the example in Excel for a better understanding (with 20 elements only).
I must select 10 elements (the highest values of variable Var.2), which fit one of the 3 options above.
Number
Position
Var.1
Var.2
1
27
C
40
2
30
B
39
Selected:
3
5
A
38
Number
Position
Var.1
Var.2
4
16
D
37
1
27
C
40
5
23
C
36
2
30
B
39
3A - 3B - 2C - 2D
6
13
A
35
3
5
A
38
7
20
D
34
4
16
D
37
3A - 3B - 1C - 3D
8
12
D
33
5
23
C
36
9
9
A
32
6
13
A
35
2A - 5B - 0C - 3D
10
1
A
31
7
20
D
34
11
21
A
30
10
9
A
32
12
35
C
29
13
14
B
28
13
14
B
28
17
6
B
25
14
8
D
27
15
7
C
26
16
6
B
25
17
40
D
24
18
26
B
23
19
29
A
22
20
31
C
21
Second option (other data set):
Number
Position
Var.1
Var.2
1
36
D
20
2
11
B
19
Selected:
3
39
A
18
Number
Position
Var.1
Var.2
4
24
D
17
1
36
D
20
5
34
B
16
2
11
B
19
3A - 3B - 2C - 2D
6
2
B
15
3
39
A
18
7
3
A
14
4
24
D
17
3A - 3B - 1C - 3D
8
32
D
13
5
34
B
16
9
28
D
12
6
2
B
15
2A - 5B - 0C - 3D
10
25
A
11
7
3
A
14
11
19
B
10
8
32
D
13
12
15
B
9
9
25
A
11
13
17
A
8
10
18
C
7
14
18
C
7
15
38
B
6
16
10
B
5
17
22
B
4
18
4
D
3
19
33
A
2
20
37
A
1
How to make the selection of these 10 elements that fit one of the 3 options using R?
Thanks,
Prof. Dr. Silvano Cesar da Costa
Universidade Estadual de Londrina
Centro de Ciências Exatas
Departamento de Estatística
Fone: (43) 3371-4346
Em sex., 20 de ago. de 2021 às 03:28, PIKAL Petr <mailto:mailto:petr.pikal using precheza.cz> escreveu:
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
$D
[1] 37 34 33 27 24 20 17 13 12 3
T inspect highest values. But here I am lost. As C is first and fourth biggest value, you follow third option and select 3 highest A, 3B 2C and 2D?
Or I do not understand at all what you really want to achieve.
Cheers
Petr
> -----Original Message-----
> From: R-help <mailto:mailto:r-help-bounces using r-project.org> On Behalf Of Silvano Cesar da
> Costa
> Sent: Thursday, August 19, 2021 10:40 PM
> To: mailto:mailto:r-help using r-project.org
> Subject: [R] Selecting elements
>
> Hi,
>
> I need to select 15 elements, always considering the highest values
> (descending order) but obeying the following configuration:
>
> 3A - 4B - 0C - 3D or
> 2A - 5B - 0C - 3D or
> 3A - 3B - 2C - 2D
>
> If I have, for example, 5 A elements as the highest values, I can only choose
> (first and third choice) or 2 (second choice) elements.
>
> how to make this selection?
>
>
> library(dplyr)
>
> Var.1 = rep(LETTERS[1:4], 10)
> Var.2 = sample(1:40, replace=FALSE)
>
> data = data.frame(Var.1, Var.2)
> (data = data[order(data$Var.2, decreasing=TRUE), ])
>
> Elements = data %>%
> arrange(desc(Var.2))
>
> Thanks,
>
> Prof. Dr. Silvano Cesar da Costa
> Universidade Estadual de Londrina
> Centro de Ciências Exatas
> Departamento de Estatística
>
> Fone: (43) 3371-4346
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> mailto:mailto: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.
More information about the R-help
mailing list