Objective: I am coming from javascript background. I am try to parse a json. json.loads
is supposed to convert stringfied values into their relevant type.
How can it be done with python 3? Purpose is eval all values with relevant type.
Scenerio: I am reading csv in python when reading csv, values are converted to strings I removed csv code becuase it was not relevant !!!
Code:
import json
x = '{ "name":"John", "age":30, "dev":"true", "trig":"1.0E-10", "res":"0.1"}'
y = json.loads(x)
print(y)
Current Output:
{
"name": "John",
"age": "30",
"dev": "true",
"trig": "1.0E-10",
"res": "0.1"
}
Expected output:
{
"name": "John",
"age": 30, // int
"dev": true, // bool
"trig": 1.0E-10, // real number
"res": 0.1 // float
}
First you need to load your json from file
file = open('data.json', 'r')
content = file.read()
file.close()
Then we can go over each value and check whether we can convert it to int
or float
or if its either 'true'
or 'false'
, if so we update specific value of our dictionary.
import json
loaded_json = json.loads(content)
def is_type(x, t):
try:
t(x)
return True
except:
return False
for k, v in loaded_json.items():
if is_type(v, int):
loaded_json[k] = int(v)
elif is_type(v, float):
loaded_json[k] = float(v)
elif v == 'true':
loaded_json[k] = True
elif v == 'false':
loaded_json[k] = False
for k, v in sorted(loaded_json.items()):
print(k, v, '//', type(v))
Output:
age 30 // <class 'int'>
dev True // <class 'bool'>
name John // <class 'str'>
res 0.1 // <class 'float'>
trig 1e-10 // <class 'float'>
Your fundamental problem is that your json data contains strings, not values (eg "dev":"true"
instead of "dev":true
). Parsing the string in javascript will hit the same problems you're seeing in Python:
(dev) go|c:\srv\tmp> node
> x = '{ "name":"John", "age":30, "dev":"true", "trig":"1.0E-10", "res":"0.1"}'
'{ "name":"John", "age":30, "dev":"true", "trig":"1.0E-10", "res":"0.1"}'
> JSON.parse(x)
{ name: 'John', age: 30, dev: 'true', trig: '1.0E-10', res: '0.1' }
> JSON.parse(x).dev
'true'
> typeof JSON.parse(x).dev
'string'
The real solution here is to fix whatever is creating such malformed json.
You can hack your way around it in Python by eg:
import ast, json
x = '{ "name":"John", "age":30, "dev":"true", "trig":"1.0E-10", "res":"0.1"}'
def evalfn(pairs):
res = {}
for key, val in pairs:
if val in {'true','false'}:
res[key] = val == 'true'
continue
try:
res[key] = ast.literal_eval(val)
except Exception as e:
res[key] = val
return res
y = json.loads(x, object_pairs_hook=evalfn)
print y
which will print
{u'trig': 1e-10, u'res': 0.1, u'age': 30, u'name': u'John', u'dev': True}
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