r - 从向量中找出所有可能的数字组合以达到给定的总和(无重复)

Question

我有一个向量“数字”，我想找出总和在 90 到 110 范围内的 1,2 或 3 个数字的所有可能组合。

我知道有很多帖子提供了解决问题的方法，但没有一个能满足我的需求。
至少在 R# 中不是

numbers <- c(40,60,20,65,45,30,5,70,100,85,75,10);
names(numbers) <- c("A","B","C","D","E","F","G","H","I","J","K","L")

结果应如下所示:

A + B
A + D
A + H
I
B + E
B + F
C + H
C + J
C + K
D + E
D + F
F + H
F + K
J + L

Answer 1

我编写了一个名为 RcppAlgos 的包这是为这些任务而构建的。有一个功能comboGeneral能够找到特定约束下的所有组合。观察:

comboBetween <- function(v, m, constraint) {
    do.call(c, lapply(1:m, function(x) {
        nums <- comboGeneral(v, x, constraintFun = "sum", 
                                   comparisonFun = c(">=", "<="), 
                                   limitConstraints = constraint)
        apply(matrix(myNames[match(nums, numbers)], 
                     ncol = x), 1, paste, collapse = " + ")
    }))
}

下面是一个例子:

numbers <- c(40,60,20,65,45,30,5,70,100,85,75,10);
myNames <- c("A","B","C","D","E","F","G","H","I","J","K","L")

comboBetween(numbers, 4, c(90, 110))
 [1] "I"             "G + J"         "G + I"         "L + J"         "L + I"         "C + H"        
 [7] "C + K"         "C + J"         "F + B"         "F + D"         "F + H"         "F + K"        
[13] "A + B"         "A + D"         "A + H"         "E + B"         "E + D"         "G + L + K"    
[19] "G + L + J"     "G + C + D"     "G + C + H"     "G + C + K"     "G + C + J"     "G + F + B"    
[25] "G + F + D"     "G + F + H"     "G + F + K"     "G + A + E"     "G + A + B"     "G + A + D"    
[31] "G + E + B"     "L + C + B"     "L + C + D"     "L + C + H"     "L + C + K"     "L + F + B"    
[37] "L + F + D"     "L + F + H"     "L + A + E"     "L + A + B"     "C + F + A"     "C + F + E"    
[43] "C + F + B"     "C + A + E"     "G + L + C + B" "G + L + C + D" "G + L + C + H" "G + L + C + K"
[49] "G + L + F + E" "G + L + F + B" "G + L + F + D" "G + L + A + E" "G + C + F + A" "G + C + F + E"
[55] "G + C + A + E" "L + C + F + A" "L + C + F + E"

它非常有效，就像它写在 C++ 中一样以获得最佳性能。