Name specifications
A name specification describes how to combine an inner and outer names. This sort of name combination arises when concatenating vectors or flattening lists. There are two possible cases:
Named vector:
vec_c(outer = c(inner1 = 1, inner2 = 2))
Unnamed vector:
vec_c(outer = 1:2)
In r-lib and tidyverse packages, these cases are errors by default, because there's no behaviour that works well for every case. Instead, you can provide a name specification that describes how to combine the inner and outer names of inputs. Name specifications can refer to:
outer: The external name recycled to the size of the input
vector.
inner: Either the names of the input vector, or a sequence of
integer from 1 to the size of the vector if it is unnamed.
name_spec, .name_spec |
A name specification for combining
inner and outer names. This is relevant for inputs passed with a
name, when these inputs are themselves named, like
See the name specification topic. |
# By default, named inputs must be length 1:
vec_c(name = 1) # ok
try(vec_c(name = 1:3)) # bad
# They also can't have internal names, even if scalar:
try(vec_c(name = c(internal = 1))) # bad
# Pass a name specification to work around this. A specification
# can be a glue string referring to `outer` and `inner`:
vec_c(name = 1:3, other = 4:5, .name_spec = "{outer}")
vec_c(name = 1:3, other = 4:5, .name_spec = "{outer}_{inner}")
# They can also be functions:
my_spec <- function(outer, inner) paste(outer, inner, sep = "_")
vec_c(name = 1:3, other = 4:5, .name_spec = my_spec)
# Or purrr-style formulas for anonymous functions:
vec_c(name = 1:3, other = 4:5, .name_spec = ~ paste0(.x, .y))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.