执行矩阵的两两比较 [英] Perform pairwise comparison of matrix
问题描述
我有一个包含 n 个变量的矩阵，我想创建一个新矩阵，它是每个向量的成对差异，但不是其本身.这是数据的示例.
I have a matrix of n variables and I want to make an new matrix that is a pairwise difference of each vector, but not of itself. Here is an example of the data.
Transportation.services Recreational.goods.and.vehicles Recreation.services Other.services
2.958003 -0.25983789 5.526694 2.8912009
2.857370 -0.03425164 5.312857 2.9698044
2.352275 0.30536569 4.596742 2.9190123
2.093233 0.65920773 4.192716 3.2567390
1.991406 0.92246531 3.963058 3.6298314
2.065791 1.06120930 3.692287 3.4422340
我尝试在下面运行 for 循环，但我知道 R 使用循环非常慢.
I tried running a for loop below, but I'm aware that R is very slow with loops.
Difference.Matrix<- function(data){
n<-2
new.cols="New Columns"
list = list()
for (i in 1:ncol(data)){
for (j in n:ncol(data)){
name <- paste("diff",i,j,data[,i],data[,j],sep=".")
new<- data[,i]-data[,j]
list[[new.cols]]<-c(name)
data<-merge(data,new)
}
n= n+1
}
results<-list(data=data)
return(results)
}
正如我之前所说，代码运行非常缓慢，甚至还没有完成一次运行.我也为初学者级别的编码道歉.我也知道这段代码将原始数据留在矩阵上，但我可以稍后将其删除.
As I said before the code is running very slow and has not even finished a single run through yet. Also I apologize for the beginner level coding. Also I am aware this code leaves the original data on the matrix, but I can delete it later.
我可以对这些数据使用应用函数或 foreach 吗?
Is it possible for me to use an apply function or foreach on this data?
推荐答案
你可以用 combn 找到对，然后用 apply 创建结果:
You can find the pairs with combn and use apply to create the result:
apply(combn(ncol(d), 2), 2, function(x) d[,x[1]] - d[,x[2]])
## [,1] [,2] [,3] [,4] [,5] [,6]
## [1,] 3.217841 -2.568691 0.0668021 -5.786532 -3.151039 2.6354931
## [2,] 2.891622 -2.455487 -0.1124344 -5.347109 -3.004056 2.3430526
## [3,] 2.046909 -2.244467 -0.5667373 -4.291376 -2.613647 1.6777297
## [4,] 1.434025 -2.099483 -1.1635060 -3.533508 -2.597531 0.9359770
## [5,] 1.068941 -1.971652 -1.6384254 -3.040593 -2.707366 0.3332266
## [6,] 1.004582 -1.626496 -1.3764430 -2.631078 -2.381025 0.2500530
您可以使用另一个 apply 添加适当的名称.这里的列名很长，这会影响格式，但标签说明了每列的区别:
You can add appropriate names with another apply. Here the column names are very long, which impairs the formatting, but the labels tell what differences are in each column:
x <- apply(combn(ncol(d), 2), 2, function(x) d[,x[1]] - d[,x[2]])
colnames(x) <- apply(combn(ncol(d), 2), 2, function(x) paste(names(d)[x], collapse=' - '))
> x
Transportation.services - Recreational.goods.and.vehicles Transportation.services - Recreation.services
[1,] 3.217841 -2.568691
[2,] 2.891622 -2.455487
[3,] 2.046909 -2.244467
[4,] 1.434025 -2.099483
[5,] 1.068941 -1.971652
[6,] 1.004582 -1.626496
Transportation.services - Other.services Recreational.goods.and.vehicles - Recreation.services
[1,] 0.0668021 -5.786532
[2,] -0.1124344 -5.347109
[3,] -0.5667373 -4.291376
[4,] -1.1635060 -3.533508
[5,] -1.6384254 -3.040593
[6,] -1.3764430 -2.631078
Recreational.goods.and.vehicles - Other.services Recreation.services - Other.services
[1,] -3.151039 2.6354931
[2,] -3.004056 2.3430526
[3,] -2.613647 1.6777297
[4,] -2.597531 0.9359770
[5,] -2.707366 0.3332266
[6,] -2.381025 0.2500530
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