How can I convert the str
representation of a dict
, such as the following string, into a dict
?
s = "{'muffin' : 'lolz', 'foo' : 'kitty'}"
I prefer not to use eval
. What else can I use?
The main reason for this, is one of my coworkers classes he wrote, converts all input into strings. I'm not in the mood to go and modify his classes, to deal with this issue.
This question is related to
python
string
dictionary
To summarize:
import ast, yaml, json, timeit
descs=['short string','long string']
strings=['{"809001":2,"848545":2,"565828":1}','{"2979":1,"30581":1,"7296":1,"127256":1,"18803":2,"41619":1,"41312":1,"16837":1,"7253":1,"70075":1,"3453":1,"4126":1,"23599":1,"11465":3,"19172":1,"4019":1,"4775":1,"64225":1,"3235":2,"15593":1,"7528":1,"176840":1,"40022":1,"152854":1,"9878":1,"16156":1,"6512":1,"4138":1,"11090":1,"12259":1,"4934":1,"65581":1,"9747":2,"18290":1,"107981":1,"459762":1,"23177":1,"23246":1,"3591":1,"3671":1,"5767":1,"3930":1,"89507":2,"19293":1,"92797":1,"32444":2,"70089":1,"46549":1,"30988":1,"4613":1,"14042":1,"26298":1,"222972":1,"2982":1,"3932":1,"11134":1,"3084":1,"6516":1,"486617":1,"14475":2,"2127":1,"51359":1,"2662":1,"4121":1,"53848":2,"552967":1,"204081":1,"5675":2,"32433":1,"92448":1}']
funcs=[json.loads,eval,ast.literal_eval,yaml.load]
for desc,string in zip(descs,strings):
print('***',desc,'***')
print('')
for func in funcs:
print(func.__module__+' '+func.__name__+':')
%timeit func(string)
print('')
Results:
*** short string ***
json loads:
4.47 µs ± 33.4 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
builtins eval:
24.1 µs ± 163 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
ast literal_eval:
30.4 µs ± 299 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
yaml load:
504 µs ± 1.29 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
*** long string ***
json loads:
29.6 µs ± 230 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
builtins eval:
219 µs ± 3.92 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
ast literal_eval:
331 µs ± 1.89 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
yaml load:
9.02 ms ± 92.2 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
Conclusion: prefer json.loads
using json.loads
:
>>> import json
>>> h = '{"foo":"bar", "foo2":"bar2"}'
>>> d = json.loads(h)
>>> d
{u'foo': u'bar', u'foo2': u'bar2'}
>>> type(d)
<type 'dict'>
If the string can always be trusted, you could use eval
(or use literal_eval
as suggested; it's safe no matter what the string is.) Otherwise you need a parser. A JSON parser (such as simplejson) would work if he only ever stores content that fits with the JSON scheme.
To OP's example:
s = "{'muffin' : 'lolz', 'foo' : 'kitty'}"
We can use Yaml to deal with this kind of non-standard json in string:
>>> import yaml
>>> s = "{'muffin' : 'lolz', 'foo' : 'kitty'}"
>>> s
"{'muffin' : 'lolz', 'foo' : 'kitty'}"
>>> yaml.load(s)
{'muffin': 'lolz', 'foo': 'kitty'}
string = "{'server1':'value','server2':'value'}"
#Now removing { and }
s = string.replace("{" ,"")
finalstring = s.replace("}" , "")
#Splitting the string based on , we get key value pairs
list = finalstring.split(",")
dictionary ={}
for i in list:
#Get Key Value pairs separately to store in dictionary
keyvalue = i.split(":")
#Replacing the single quotes in the leading.
m= keyvalue[0].strip('\'')
m = m.replace("\"", "")
dictionary[m] = keyvalue[1].strip('"\'')
print dictionary
no any libs are used:
dict_format_string = "{'1':'one', '2' : 'two'}"
d = {}
elems = filter(str.isalnum,dict_format_string.split("'"))
values = elems[1::2]
keys = elems[0::2]
d.update(zip(keys,values))
NOTE: As it has hardcoded split("'")
will work only for strings where data is "single quoted".
https://docs.python.org/3.8/library/json.html
JSON can solve this problem though its decoder wants double quotes around keys and values. If you don't mind a replace hack...
import json
s = "{'muffin' : 'lolz', 'foo' : 'kitty'}"
json_acceptable_string = s.replace("'", "\"")
d = json.loads(json_acceptable_string)
# d = {u'muffin': u'lolz', u'foo': u'kitty'}
NOTE that if you have single quotes as a part of your keys or values this will fail due to improper character replacement. This solution is only recommended if you have a strong aversion to the eval solution.
More about json single quote: jQuery.parseJSON throws “Invalid JSON” error due to escaped single quote in JSON
Use json
. the ast
library consumes a lot of memory and and slower. I have a process that needs to read a text file of 156Mb. Ast
with 5 minutes delay for the conversion dictionary json
and 1 minutes using 60% less memory!
Source: Stackoverflow.com