I have a string that contains a list of sets -

'[{13,18},{14,19}]'

I want it to be like this -

['[13,18]','[14,19]']

When I use ast.literal_eval() the order of the sets gets changed -

>>> 
>>> l1='[{13,18},{14,19}]'
>>> 
>>> 
>>> ast.literal_eval(l1)
[{18, 13}, {19, 14}]
>>> 

Please suggest how can I keep the order of the elements inside the set. Thank you.

CodePudding user response：

sets are inherently unordered ("arbitrarily ordered" is more precise), so the moment the set is parsed, the order is lost. If you can be sure none of the values contain a { or } that does not denote a set, and the desired end result is a list of lists (rather than the list of sets represented by your string) the solution is simple:

braces_to_brackets = str.maketrans('{}', '[]')  # Done once up front

mystr = '[{13,18},{14,19}]'
fixed_str = mystr.translate(braces_to_brackets)  # Replace curly braces with square brackets
parsed = ast.literal_eval(fixed_str)

which produces a parsed of [[13, 18], [14, 19]], with the order preserved.

Try it online!

CodePudding user response：

With a couple of judicious replacements you could just do this:

from ast import literal_eval

mystring = '[{13,18},{14,19}]'
mystring = mystring.replace('{', "'[").replace('}', "]'")
myval = literal_eval(mystring)
print(myval)

Output:

['[13,18]', '[14,19]']