yaml.load {yaml} | R Documentation |
This function implements the Syck YAML parser for R. It parses a YAML string into R objects.
yaml.load(string, as.named.list = TRUE, handlers = NULL)
string |
the YAML string to be parsed (character vector of length 1) |
as.named.list |
whether or not to return a named list for maps (TRUE by default) |
handlers |
named list of custom handler functions for YAML types (see Details). |
Sequences of uniform data (i.e. a sequence of integers) are converted into vectors. If
the sequence is not uniform, it's returned as a list. Maps are converted into named lists
by default, and all the keys in the map are converted to strings. If you don't want the
keys to be coerced into strings, set as.named.list
to FALSE. When it's FALSE, a
list will be returned with an additional attribute named 'keys', which is a list of the
un-coerced keys in the map (in the same order as the main list).
You can specify custom handler functions via the handlers
argument. This argument
must be a named list of functions, where the names are the YAML types (i.e., 'int', 'float',
'timestamp#iso8601', etc). The functions you provide will be passed one argument. Custom
handler functions for string types (all types except sequence and map) will receive a
character vector of length 1. Custom sequence functions will be passed a list of objects.
Custom map functions will be passed the object that the internal map handler creates, which
is either a named list or a list with a 'keys' attribute (depending on as.named.list
).
ALL functions you provide must return an object. See the examples for custom handler use.
If the root YAML object is a map, a named list or list with an attribute of 'keys' is returned. If the root object is a sequence, a list or vector is returned, depending on the contents of the sequence. A vector of length 1 is returned for single objects.
Jeremy Stephens <jeremy.stephens@vanderbilt.edu
YAML: http://yaml.org Syck YAML Parser: http://whytheluckystiff.net/syck/
yaml.load("- hey\n- hi\n- hello") yaml.load("foo: 123\nbar: 456") yaml.load("- foo\n- bar\n- 3.14") yaml.load("foo: bar\n123: 456", as.named.list = FALSE) ## Not run: yaml.load(readLines("foo.yml")) ## End(Not run) # custom string-type handler my.float.handler <- function(x) { as.numeric(x) + 123 } yaml.load("123.456", handlers=list("float#fix"=my.float.handler)) # custom sequence handler yaml.load("- 1\n- 2\n- 3", handlers=list(seq=function(x) { as.integer(x) + 3 })) # custom map handler yaml.load("foo: 123", handlers=list(map=function(x) { x$foo <- x$foo + 123; x })) # handling custom types yaml.load("!sqrt 555", handlers=list(sqrt=function(x) { sqrt(as.integer(x)) })) yaml.load("!foo\n- 1\n- 2", handlers=list(foo=function(x) { as.integer(x) + 1 })) yaml.load("!bar\none: 1\ntwo: 2", handlers=list(foo=function(x) { x$one <- "one"; x }))