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| """Utilities for dealing with writing json strings.
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| json_utils wraps json.dump and json.dumps so that they can be used to safely
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| control the precision of floats when writing to json strings or files.
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| """
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| import json
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| import re
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| def FormatFloat(json_str, float_digits):
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| pattern = re.compile(r'\d+\.\d+')
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| float_repr = '{:.' + '{}'.format(float_digits) + 'f}'
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| def MRound(match):
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| return float_repr.format(float(match.group()))
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| return re.sub(pattern, MRound, json_str)
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| def Dump(obj, fid, float_digits=-1, **params):
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| """Wrapper of json.dump that allows specifying the float precision used.
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| Args:
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| obj: The object to dump.
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| fid: The file id to write to.
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| float_digits: The number of digits of precision when writing floats out.
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| **params: Additional parameters to pass to json.dumps.
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| """
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| json_str = Dumps(obj, float_digits, **params)
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| fid.write(json_str)
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| def Dumps(obj, float_digits=-1, **params):
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| """Wrapper of json.dumps that allows specifying the float precision used.
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| Args:
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| obj: The object to dump.
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| float_digits: The number of digits of precision when writing floats out.
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| **params: Additional parameters to pass to json.dumps.
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| Returns:
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| output: JSON string representation of obj.
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| """
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| json_str = json.dumps(obj, **params)
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| if float_digits > -1:
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| json_str = FormatFloat(json_str, float_digits)
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| return json_str
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| def PrettyParams(**params):
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| """Returns parameters for use with Dump and Dumps to output pretty json.
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| Example usage:
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| ```json_str = json_utils.Dumps(obj, **json_utils.PrettyParams())```
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| ```json_str = json_utils.Dumps(
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| obj, **json_utils.PrettyParams(allow_nans=False))```
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| Args:
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| **params: Additional params to pass to json.dump or json.dumps.
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| Returns:
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| params: Parameters that are compatible with json_utils.Dump and
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| json_utils.Dumps.
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| """
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| params['float_digits'] = 4
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| params['sort_keys'] = True
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| params['indent'] = 2
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| params['separators'] = (',', ': ')
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| return params
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|
