Mutate variables in a draws object.
mutate_variables(.x, ...)
# S3 method for draws_matrix
mutate_variables(.x, ...)
# S3 method for draws_array
mutate_variables(.x, ...)
# S3 method for draws_df
mutate_variables(.x, ...)
# S3 method for draws_list
mutate_variables(.x, ...)
# S3 method for draws_rvars
mutate_variables(.x, ...)(draws) A draws object.
Name-value pairs of expressions, each with either length 1 or the
same length as in the entire input (i.e., number of iterations or draws).
The name of each argument will be the name of a new variable, and the value
will be its corresponding value. Use a NULL value in mutate_variables
to drop a variable. New variables overwrite existing variables of the same
name.
Returns a draws object of the same format as .x, with variables mutated
according to the expressions provided in ....
In order to mutate variables in draws_matrix and draws_array objects,
they are transformed to draws_df objects first and then transformed back
after mutation. As those transformations are quite expensive for larger
number of draws, we recommend using mutate_variables on draws_df and
draws_list objects if speed is an issue.
In draws_rvars objects, the output of each expression in ... is
coerced to an rvar object if it is not already one using as_rvar().
x <- as_draws_df(example_draws())
x <- subset(x, variable = c("mu", "tau"))
mutate_variables(x, tau2 = tau^2)
#> # A draws_df: 100 iterations, 4 chains, and 3 variables
#> mu tau tau2
#> 1 2.01 2.8 7.7
#> 2 1.46 7.0 48.7
#> 3 5.81 9.7 93.6
#> 4 6.85 4.8 22.9
#> 5 1.81 2.8 8.1
#> 6 3.84 4.1 16.7
#> 7 5.47 4.0 15.6
#> 8 1.20 1.5 2.2
#> 9 0.15 3.9 15.4
#> 10 7.17 1.8 3.1
#> # ... with 390 more draws
#> # ... hidden reserved variables {'.chain', '.iteration', '.draw'}
mutate_variables(x, scale = 1.96 * tau, lower = mu - scale)
#> # A draws_df: 100 iterations, 4 chains, and 4 variables
#> mu tau scale lower
#> 1 2.01 2.8 5.4 -3.4
#> 2 1.46 7.0 13.7 -12.2
#> 3 5.81 9.7 19.0 -13.2
#> 4 6.85 4.8 9.4 -2.5
#> 5 1.81 2.8 5.6 -3.8
#> 6 3.84 4.1 8.0 -4.2
#> 7 5.47 4.0 7.7 -2.3
#> 8 1.20 1.5 2.9 -1.7
#> 9 0.15 3.9 7.7 -7.6
#> 10 7.17 1.8 3.5 3.7
#> # ... with 390 more draws
#> # ... hidden reserved variables {'.chain', '.iteration', '.draw'}