Error: Numerical expression has 6 elements: only the first used and Warning in GA

Question

这是我的代码，我想知道为什么会有警告消息说 "number of items to replace is not a multiple of replacement length"?

    library(GA)
    library(readxl)
    > data1 <- 
    read_excel("C:/Users/nadiahalim/OneDrive/CS954/Scheduling/data1.xlsx")
    > View(data1)
    > data1

data1 的输出

# A tibble: 6 x 4
   Jobj    Pj    Dj    Wj
  <dbl> <dbl> <dbl> <dbl>
1     1    25    61     3
2     2     7   102     7
3     3    42    86     1
4     4    36    44     3
5     5    18   150     1
6     6    29   134     4

我想对 Jobj 进行重新排序，使其给出由 Cj 表示的最短完成时间。 For循环已在我的代码中使用如下：

Cj=0
i<- sample(data1$Jobj)
for(i in 1:i){
fitness <-function(j){
for(j in data1$Jobj){
Cj[j] <- data1$Pj[j]+sum(Cj[j-1])
}
print(Cj)
}
fitness()

此代码的输出

numerical expression has 6 elements: only the first used[1]  25  32  74 110 128 157
[1]  25  32  74 110 128 157
[1]  25  32  74 110 128 157
[1]  25  32  74 110 128 157
[1]  25  32  74 110 128 157

然后，我运行求GA码：

GA <- ga(type = "permutation", fitness = fitness, lower = 1, upper = 6, maxiter= 5, run = 20, optim = TRUE)

GA 的输出如下，警告指出要替换的项目数不是替换长度的倍数

    number of items to replace is not a multiple of replacement length[1]  25  32  74 110 128 157
number of items to replace is not a multiple of replacement lengthGA | iter = 3 | Mean = 25 | Best = 25
[1]  25  32  74 110 128 157
number of items to replace is not a multiple of replacement length[1]  25  32  74 110 128 157
number of items to replace is not a multiple of replacement length[1]  25  32  74 110 128 157

然后我运行为了

summary(GA)

汇总 GA 的输出

-- Genetic Algorithm ------------------- 

GA settings: 
Type                  =  permutation 
Population size       =  50 
Number of generations =  5 
Elitism               =  2 
Crossover probability =  0.8 
Mutation probability  =  0.1 

GA results: 
Iterations             = 5 
Fitness function value = 25 
Solutions = 
      x1 x2 x3 x4 x5 x6
[1,]   4  1  6  3  5  2
[2,]   6  3  1  5  4  2
[3,]   6  2  3  4  1  5
[4,]   3  6  4  1  5  2
[5,]   4  6  2  1  5  3
[6,]   5  3  4  1  2  6
[7,]   2  1  6  3  5  4
[8,]   4  1  6  3  2  5
[9,]   3  6  1  2  5  4
[10,]  3  6  2  1  5  4
 ...                   
[35,]  4  5  6  2  1  3
[36,]  3  4  5  6  2  1

当我运行进行摘要（GA）时，它似乎有效，但我对警告感到好奇 messages.I 如果有人能帮助我解决这个问题，我将不胜感激。提前谢谢你。

Answer 1

您在 fitness 函数中尝试执行的操作无需 for 循环即可轻松实现。

例如，您从 for 循环获得的输出是

#[1] 25  32  74 110 128 157

并使用 cumsum 我们得到同样的结果。

cumsum(data1$Pj)
#[1]  25  32  74 110 128 157

然而，主要问题是 fitness 函数应该 return 只有一个值，而不是像 cumsum 这样的值向量。所以如果你把函数改成这样

fitness <- function(j) sum(j)

你可以做到：

fitness(data1$Pj)
#[1] 157

library(GA)
GA <- ga(type = "permutation", fitness = fitness, lower = 1, upper = 6, 
         maxiter= 5, run = 20, optim = TRUE)

其中 return 没有警告。

Error: Numerical expression has 6 elements: only the first used and Warning in GA

Error: Numerical expression has 6 elements: only the first used and Warning in GA

r

for-loop

permutation

genetic-algorithm