semibruin - 7 months ago 38

R Question

Let

`x = c(1, 2, 3)`

`bs`

`splines`

`R`

`x`

`require(splines)`

x <- c(1, 2, 3)

bs.x <- bs(x, knots = c(1.5, 2.5))

The output

`bs.x`

`1 2 3 4 5`

[1,] 0.00000000 0.0000000 0.0000000 0.00000000 0

[2,] 0.05555556 0.4444444 0.4444444 0.05555556 0

[3,] 0.00000000 0.0000000 0.0000000 0.00000000 1

attr(,"degree")

[1] 3

attr(,"knots")

[1] 1.5 2.5

attr(,"Boundary.knots")

[1] 1 3

attr(,"intercept")

[1] FALSE

attr(,"class")

[1] "bs" "basis" "matrix"

Clearly, besides the basis matrix,

`bs.x`

`Matrix(bs.x)`

`Error in as(x, "matrix") :`

internal problem in as(): “bs” is(object, "matrix") is

TRUE, but the metadata asserts that the 'is' relation is FALSE

I guess this is because

`matrix`

`bs.x`

`bs.x <- matrix(as.numeric(bs.x), nr = nrow(bs.x))`

Is there a better alternative? Thanks in advance.

Answer

Not a whole lot better, but

```
attributes(bs.x) <- attributes(bs.x)["dim"]
```

seems to work. (Reassigns the attributes of `bs.x`

to be *only* the `dim`

attribute.)