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README.rst

UltraJSON

https://travis-ci.org/esnme/ultrajson.svg?branch=master

UltraJSON is an ultra fast JSON encoder and decoder written in pure C with bindings for Python 2.5+ and 3.

For a more painless day to day C/C++ JSON decoder experience please checkout ujson4c, based on UltraJSON.

Please checkout the rest of the projects in the Ultra series:

To install it just run Pip as usual:

$ pip install ujson

Usage

May be used as a drop in replacement for most other JSON parsers for Python:

>>> import ujson
>>> ujson.dumps([{"key": "value"}, 81, True])
'[{"key":"value"},81,true]'
>>> ujson.loads("""[{"key": "value"}, 81, true]""")
[{u'key': u'value'}, 81, True]

Encoder options

encode_html_chars

Used to enable special encoding of "unsafe" HTML characters into safer Unicode sequences. Default is false:

>>> ujson.dumps("<script>John&Doe", encode_html_chars=True)
'"\\u003cscript\\u003eJohn\\u0026Doe"'

ensure_ascii

Limits output to ASCII and escapes all extended characters above 127. Default is true. If your end format supports UTF-8 setting this option to false is highly recommended to save space:

>>> ujson.dumps(u"\xe5\xe4\xf6")
'"\\u00e5\\u00e4\\u00f6"'
>>> ujson.dumps(u"\xe5\xe4\xf6", ensure_ascii=False)
'"\xc3\xa5\xc3\xa4\xc3\xb6"'

double_precision

Controls how many decimals to encode for double or decimal values. Default is 9:

>>> ujson.dumps(math.pi)
'3.1415926536'
>>> ujson.dumps(math.pi, double_precision=1)
'3.1'
>>> ujson.dumps(math.pi, double_precision=0)
'3'
>>> ujson.dumps(math.pi, double_precision=4)
'3.1416'

escape_forward_slashes

Controls whether forward slashes (/) are escaped. Default is True:

>>> ujson.dumps("http://esn.me")
'"http:\/\/esn.me"'
>>> ujson.dumps("http://esn.me", escape_forward_slashes=False)
'"http://esn.me"'

indent

Controls whether indention ("pretty output") is enabled. Default is 0 (disabled):

>>> ujson.dumps({"foo": "bar"})
'{"foo":"bar"}'
>>> ujson.dumps({"foo": "bar"}, indent=4)
{
    "foo":"bar"
}

Decoders options

precise_float

Set to enable usage of higher precision (strtod) function when decoding string to double values. Default is to use fast but less precise builtin functionality:

>>> ujson.loads("4.56")
4.5600000000000005
>>> ujson.loads("4.56", precise_float=True)
4.5599999999999996

Test machine:

Linux 3.13.0-66-generic x86_64 #108-Ubuntu SMP Wed Oct 7 15:20:27 UTC 2015

Versions:

  • CPython 2.7.6 (default, Jun 22 2015, 17:58:13) [GCC 4.8.2]
  • blist : 1.3.6
  • simplejson: 3.8.1
  • ujson : 1.34 (0c52200eb4e2d97e548a765d5f089858c41967b0)
  • yajl : 0.3.5
  ujson yajl simplejson json
Array with 256 doubles        
encode 3508.19 5742.00 3232.38 3309.09
decode 25103.37 11257.83 11696.26 11871.04
Array with 256 UTF-8 strings        
encode 3189.71 2717.14 2006.38 2961.72
decode 1354.94 630.54 356.35 344.05
Array with 256 strings        
encode 18127.47 12537.39 12541.23 20001.00
decode 23264.70 12788.85 25427.88 9352.36
Medium complex object        
encode 10519.38 5021.29 3686.86 4643.47
decode 9676.53 5326.79 8515.77 3017.30
Array with 256 True values        
encode 105998.03 102067.28 44758.51 60424.80
decode 163869.96 78341.57 110859.36 115013.90
Array with 256 dict{string, int} pairs        
encode 13471.32 12109.09 3876.40 8833.92
decode 16890.63 8946.07 12218.55 3350.72
Dict with 256 arrays with 256 dict{string, int} pairs        
encode 50.25 46.45 13.82 29.28
decode 33.27 22.10 27.91 10.43
Dict with 256 arrays with 256 dict{string, int} pairs, outputting sorted keys        
encode 27.19   7.75 2.39
Complex object        
encode 577.98   387.81 470.02
decode 496.73 234.44 151.00 145.16

Versions:

  • CPython 3.4.3 (default, Oct 14 2015, 20:28:29) [GCC 4.8.4]
  • blist : 1.3.6
  • simplejson: 3.8.1
  • ujson : 1.34 (0c52200eb4e2d97e548a765d5f089858c41967b0)
  • yajl : 0.3.5
  ujson yajl simplejson json
Array with 256 doubles        
encode 3477.15 5732.24 3016.76 3071.99
decode 23625.20 9731.45 9501.57 9901.92
Array with 256 UTF-8 strings        
encode 1995.89 2151.61 1771.98 1817.20
decode 1425.04 625.38 327.14 305.95
Array with 256 strings        
encode 25461.75 12188.64 13054.76 14429.81
decode 21981.31 17014.22 23869.48 22483.58
Medium complex object        
encode 10821.46 4837.04 3114.04 4254.46
decode 7887.77 5126.67 4934.60 6204.97
Array with 256 True values        
encode 100452.86 94639.42 46657.63 60358.63
decode 148312.69 75485.90 88434.91 116395.51
Array with 256 dict{string, int} pairs        
encode 11698.13 8886.96 3043.69 6302.35
decode 10686.40 7061.77 5646.80 7702.29
Dict with 256 arrays with 256 dict{string, int} pairs        
encode 44.26 34.43 10.40 21.97
decode 28.46 23.95 18.70 22.83
Dict with 256 arrays with 256 dict{string, int} pairs, outputting sorted keys        
encode 33.60   6.94 22.34
Complex object        
encode 432.30   351.47 379.34
decode 434.40 221.97 149.57 147.79
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