Joel B - 7 months ago 22

R Question

I have a matrix of correlation coefficients (called

`input_matrix`

`| A | B | C | D`

------ | ------ | ------ | ------ | ------

area_1 | 0.870 | 0.435 | 0.968 | 0.679

area_2 | 0.456 | 0.259 | 0.906 | 0.467

area_3 | 0.298 | 0.256 | 0.457 | 0.768

area_4 | 0.994 | 0.987 | 0.365 | 0.765

I wanted to know how to find the maximum coefficient from the matrix diagonal and to store the column and row name info next to it (like in the desired output below). I have found the

`diag2vec()`

`Area | Cat | coeff`

------ | ------ | ------

area_1 | A | 0.870

Answer

Here is your data:

```
(x <- matrix(
c(0.870, 0.435, 0.968, 0.679,
0.456, 0.259, 0.906, 0.467,
0.298, 0.256, 0.457, 0.768,
0.994, 0.987, 0.365, 0.765),
nrow = 4,
dimnames = list(area = 1:4, category = letters[1:4])
))
## category
## area a b c d
## 1 0.870 0.456 0.298 0.994
## 2 0.435 0.259 0.256 0.987
## 3 0.968 0.906 0.457 0.365
## 4 0.679 0.467 0.768 0.765
```

This is the diagonal, and the position of its maximum:

```
diag_x <- diag(x)
i <- which.max(diag_x)
```

Here are the values that you want:

```
data.frame(
area = rownames(x)[i],
category = colnames(x)[i],
coeff = x[i, i]
)
## area category coeff
## 1 1 a 0.87
```