Try to access elements and return default values if not found.
In contrast to [at()], this function provides a less stricter element
access, that is, it remains valid even if elements don't exist.
peek_at(.x, ...)
# S3 method for Container
peek_at(.x, ..., .default = NULL)
# S3 method for dict.table
peek_at(.x, ..., .default = NULL)an R object of the respective class.
indices of elements to be extracted
value to be returned if peeked value does not exist.
For Container, returns the value at the given indices or (if not
found) the given default value.
For dict.table, returns the columns at the given indices or (if not
found) columns with the given default value.
peek_at tries to access specific values.
at() for strict element extraction
# Container
co = container(a = 1, 2, b = 3, 4)
peek_at(co, 1)
#> [a = 1]
peek_at(co, "a")
#> [a = 1]
peek_at(co, "x")
#> []
peek_at(co, "x", .default = 0)
#> [x = 0]
peek_at(co, "a", "x", 2, 9, .default = -1)
#> [a = 1, x = -1, 2, -1]
# Dict
d = dict(a = 1, b = 1:3)
peek_at(d, "b")
#> {b = (1L 2L 3L)}
peek_at(d, "x")
#> {}
peek_at(d, "x", .default = 4:7)
#> {x = (4L 5L 6L 7L)}
# dict.table
dit = dict.table(a = 1:3, b = 4:6)
peek_at(dit, "a")
#> <dict.table> with 3 rows and 1 column
#> a
#> 1: 1
#> 2: 2
#> 3: 3
peek_at(dit, 1)
#> <dict.table> with 3 rows and 1 column
#> a
#> 1: 1
#> 2: 2
#> 3: 3
peek_at(dit, 3)
#> <dict.table> with 0 rows and 0 columns
#> Null data.table (0 rows and 0 cols)
peek_at(dit, "x")
#> <dict.table> with 0 rows and 0 columns
#> Null data.table (0 rows and 0 cols)
peek_at(dit, "x", .default = 0)
#> <dict.table> with 3 rows and 1 column
#> x
#> 1: 0
#> 2: 0
#> 3: 0
peek_at(dit, "a", "x", .default = 0)
#> <dict.table> with 3 rows and 2 columns
#> a x
#> 1: 1 0
#> 2: 2 0
#> 3: 3 0