Reading YAML and JSON Strings¶

Parsing text with Node::parse()¶

Node.parse() parses YAML and JSON strings into a Node tree.

yaml_txt = "mykey: 42.0"

n = conduit.Node()
n.parse(yaml_txt,"yaml")

print(n["mykey"])
print(n.schema())

 42.0
 
 {
   "mykey": {"dtype":"float64", "number_of_elements": 1, "offset": 0, "stride": 8, "element_bytes": 8, "endianness": "little"}
 }

json_txt = '{"mykey": 42.0}'

n = conduit.Node()
n.parse(json_txt,"json")

print(n["mykey"])
print(n.schema())

 42.0
 
 {
   "mykey": {"dtype":"float64", "number_of_elements": 1, "offset": 0, "stride": 8, "element_bytes": 8, "endianness": "little"}
 }

The first argument is the string to parse and the second argument selects the protocol to use when parsing.

Valid Protocols: json, conduit_json, conduit_base64_json, yaml.

json and yaml protocols parse pure JSON or YAML strings. For leaf nodes wide types such as int64, uint64, and float64 are inferred.

Homogeneous numeric lists are parsed as Conduit arrays.

yaml_txt = "myarray: [0.0, 10.0, 20.0, 30.0]"

n = conduit.Node()
n.parse(yaml_txt,"yaml")

print(n["myarray"])

print(n.fetch("myarray").schema())

 [ 0. 10. 20. 30.]
 {"dtype":"float64", "number_of_elements": 4, "offset": 0, "stride": 8, "element_bytes": 8, "endianness": "little"}

conduit_json parses JSON with conduit data type information, allowing you to specify bitwidth style types, strides, etc.
conduit_base64_json combines the conduit_json protocol with an embedded base64-encoded data block

Generators¶

Using Generator instances¶

Node.parse() is sufficient for most use cases, but you can also use a Generator instance to parse JSON and YAML. Additionally, Generators can parse a conduit JSON schema and bind it to in-core data.

g = conduit.Generator("{test: {dtype: float64, value: 100.0}}",
                      "conduit_json")
n = conduit.Node()
g.walk(n)
print(n["test"])
print(n)

 100.0
 
 {
   "test": 100.0
 }

Like Node::parse(), Generators can also parse pure JSON or YAML. For leaf nodes: wide types such as int64, uint64, and float64 are inferred.

g = conduit.Generator("{test: 100.0}",
                      "json")
n = conduit.Node()
g.walk(n)
print(n["test"])
print(n)

g = conduit.Generator("test: 100.0",
                      "yaml")
n = conduit.Node()
g.walk(n)
print(n["test"])
print(n)

 100.0
 
 {
   "test": 100.0
 }