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JavaScript Object Notation, in short JSON, is a very common human readable and structured data format. GNU Octave supports encoding and decoding this format with the following two functions.
Encode Octave data types into JSON text.
The input object is an Octave variable to encode.
The output JSON_txt is the JSON text that contains the result of encoding object.
If the value of the option "ConvertInfAndNaN"
is true then NaN
,
NA
, -Inf
, and Inf
values will be converted to
"null"
in the output. If it is false then they will remain as their
original values. The default value for this option is true.
If the value of the option "PrettyPrint"
is true, the output text will
have indentations and line feeds. If it is false, the output will be condensed
and written without whitespace. The default value for this option is false.
Programming Notes:
"\n"
), use
single-quoted strings.
"\0"
) in a
double-quoted string will be dropped during encoding.
int8
and then decode it, you will get a double
.
This table shows the conversions from Octave data types to JSON data types:
Octave data type | JSON data type |
---|---|
logical scalar | Boolean |
logical vector | Array of Boolean, reshaped to row vector |
logical array | nested Array of Boolean |
numeric scalar | Number |
numeric vector | Array of Number, reshaped to row vector |
numeric array | nested Array of Number |
NaN , NA , Inf , -Inf when "ConvertInfAndNaN" = true | "null" |
NaN , NA , Inf , -Inf when "ConvertInfAndNaN" = false | "NaN" , "NaN" ,
"Infinity" , "-Infinity" |
empty array | "[]" |
character vector | String |
character array | Array of String |
empty character array | "" |
cell scalar | Array |
cell vector | Array, reshaped to row vector |
cell array | Array, flattened to row vector |
struct scalar | Object |
struct vector | Array of Object, reshaped to row vector |
struct array | nested Array of Object |
classdef object | Object |
Examples:
jsonencode ([1, NaN; 3, 4]) ⇒ [[1,null],[3,4]]
jsonencode ([1, NaN; 3, 4], "ConvertInfAndNaN", false) ⇒ [[1,NaN],[3,4]]
## Escape characters inside a single-quoted string jsonencode ('\0\a\b\t\n\v\f\r') ⇒ "\\0\\a\\b\\t\\n\\v\\f\\r"
## Escape characters inside a double-quoted string jsonencode ("\a\b\t\n\v\f\r") ⇒ "\u0007\b\t\n\u000B\f\r"
jsonencode ([true; false], "PrettyPrint", true) ⇒ ans = [ true, false ]
jsonencode (['foo', 'bar'; 'foo', 'bar']) ⇒ ["foobar","foobar"]
jsonencode (struct ('a', Inf, 'b', [], 'c', struct ())) ⇒ {"a":null,"b":[],"c":{}}
jsonencode (struct ('structarray', struct ('a', {1; 3}, 'b', {2; 4}))) ⇒ {"structarray":[{"a":1,"b":2},{"a":3,"b":4}]}
jsonencode ({'foo'; 'bar'; {'foo'; 'bar'}}) ⇒ ["foo","bar",["foo","bar"]]
jsonencode (containers.Map({'foo'; 'bar'; 'baz'}, [1, 2, 3])) ⇒ {"bar":2,"baz":3,"foo":1}
See also: jsondecode.
Decode text that is formatted in JSON.
The input JSON_txt is a string that contains JSON text.
The output object is an Octave object that contains the result of decoding JSON_txt.
For more information about the options "ReplacementStyle"
and
"Prefix"
,
see matlab.lang.makeValidName
.
If the value of the option "makeValidName"
is false then names
will not be changed by matlab.lang.makeValidName
and the
"ReplacementStyle"
and "Prefix"
options will be ignored.
NOTE: Decoding and encoding JSON text is not guaranteed to reproduce the
original text as some names may be changed by matlab.lang.makeValidName
.
This table shows the conversions from JSON data types to Octave data types:
JSON data type | Octave data type |
---|---|
Boolean | scalar logical |
Number | scalar double |
String | vector of characters |
Object | scalar struct (field names of the struct may be different from the keys of the JSON object due to matlab_lang_makeValidName |
null, inside a numeric array | NaN |
null, inside a non-numeric array | empty double array [] |
Array, of different data types | cell array |
Array, of Booleans | logical array |
Array, of Numbers | double array |
Array, of Strings | cell array of character vectors (cellstr ) |
Array of Objects, same field names | struct array |
Array of Objects, different field names | cell array of scalar structs |
Examples:
jsondecode ('[1, 2, null, 3]') ⇒ ans = 1 2 NaN 3
jsondecode ('["foo", "bar", ["foo", "bar"]]') ⇒ ans = { [1,1] = foo [2,1] = bar [3,1] = { [1,1] = foo [2,1] = bar } }
jsondecode ('{"nu#m#ber": 7, "s#tr#ing": "hi"}', ... 'ReplacementStyle', 'delete') ⇒ scalar structure containing the fields: number = 7 string = hi
jsondecode ('{"nu#m#ber": 7, "s#tr#ing": "hi"}', ... 'makeValidName', false) ⇒ scalar structure containing the fields: nu#m#ber = 7 s#tr#ing = hi
jsondecode ('{"1": "one", "2": "two"}', 'Prefix', 'm_') ⇒ scalar structure containing the fields: m_1 = one m_2 = two
See also: jsonencode, matlab.lang.makeValidName.
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