R: Examples for 'stats::formula'

### ** Examples

class(fo <- y ~ x1*x2) # "formula"

[1] "formula"

fo

y ~ x1 * x2
<environment: 0x55ccff66c8a0>

typeof(fo)  # R internal : "language"

[1] "language"

terms(fo)

y ~ x1 * x2
attr(,"variables")
list(y, x1, x2)
attr(,"factors")
   x1 x2 x1:x2
y   0  0     0
x1  1  0     1
x2  0  1     1
attr(,"term.labels")
[1] "x1"    "x2"    "x1:x2"
attr(,"order")
[1] 1 1 2
attr(,"intercept")
[1] 1
attr(,"response")
[1] 1
attr(,".Environment")
<environment: 0x55ccff66c8a0>

environment(fo)

<environment: 0x55ccff66c8a0>

environment(as.formula("y ~ x"))

<environment: 0x55ccff66c8a0>

environment(as.formula("y ~ x", env = new.env()))

<environment: 0x55ccfdcb2090>

## Create a formula for a model with a large number of variables:
xnam <- paste0("x", 1:25)
(fmla <- as.formula(paste("y ~ ", paste(xnam, collapse= "+"))))

y ~ x1 + x2 + x3 + x4 + x5 + x6 + x7 + x8 + x9 + x10 + x11 + 
    x12 + x13 + x14 + x15 + x16 + x17 + x18 + x19 + x20 + x21 + 
    x22 + x23 + x24 + x25
<environment: 0x55ccff66c8a0>

## Equivalent with reformulate():
fmla2 <- reformulate(xnam, response = "y")
stopifnot(identical(fmla, fmla2))

Examples for 'stats::formula'

Model Formulae