在R中，根据约束条件生成模型的所有可能解决方案 [英] In R, generating every possible solution to a model, based on constraints

问题描述

在R中，我试图生成一个矩阵，该矩阵显示模型的结果以及用于求解它们的值-所有这些均受约束.每种可能的解决方案.一个示例模型:

In R, I’m trying to generate a matrix that shows results from a model and the values used to solve them- all of which are constrained. Every possible solution. An example model:

Model = a ^ 2 + b ^ 2 + c ^ 2 + d ^ 2

Model= a^2+b^2+c^2+d^2

位置:

20≤型号≤30

a = 1

2≤b≤3

2≤c≤3

3≤d≤4

我希望输出看起来像这样:

I’d like the output to look like this:

    [a] [b] [c] [d] [Model]
[1]  1   3   2   3    23
[2]  1   2   2   4    25
[3]  1   3   3   3    28
[4]  1   2   3   3    23

顺序无关紧要.我只想要可行的[整数]值的完整排列.有什么包装或帮助您可以指明我的方​​向吗?

Order doesn't matter. I just want the full permutation of feasible [integer] values. Any packages or help you could point my way?

在我的示例情况下，我想基于设置的参数生成所有可能有效的输入(a，b，c，d).我只希望输出方程(模型)的值在20到30之间.在这种情况下，根据我设置的条件，只能有4个解.

In my example case, I want to generate all possible inputs(a,b,c,d) that hold valid, based on the parameters I set. I only want values from my output equation (Model) between 20 and 30. In this case, only 4 solutions are possible based on the criteria I'm setting.

推荐答案

假设您只在寻找整数解，则可以使用expand.grid()

Assuming you're only looking for integer solutions, you can use expand.grid()

dd <- expand.grid(a=1, b=2:3, c=2:3, d=3:4)
m <- with(dd, a^2+b^2+c^2+d^2)
inside <- function(x, a,b) a<=x & x<=b
cbind(dd, m)[inside(m, 20, 30),]

#   a b c d  m
# 2 1 3 2 3 23
# 3 1 2 3 3 23
# 4 1 3 3 3 28
# 5 1 2 2 4 25
# 6 1 3 2 4 30
# 7 1 2 3 4 30

(您说您想要的值是< = 30，但您的示例中似乎遗漏了30的值，可以更改要打开间隔的inside()函数)

(you said you want values <=30 but you seem to have left out the 30's in your example, you can change the inside() function of you want an open interval)

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