I have strings which look like this one:
"(8, 12.25), (13, 15), (16.75, 18.5)"
and I would like to convert each of them into a python data structure. Preferably a list (or tuple) of tuples containing a pair of float values.
I could do that with eval("(8, 12.25), (13, 15), (16.75, 18.5)")
which gives me a t开发者_StackOverflow社区uple of tuples, but I don't think naively evaluating external information would be a wise decision.
So I wondered what an elegant pythonic solution might look like.
>>> import ast
>>> print ast.literal_eval("(8, 12.25), (13, 15), (16.75, 18.5)")
((8, 12.25), (13, 15), (16.75, 18.5))
def parse(s):
tuples = s.split('), ')
out = []
for x in tuples:
a,b = x.strip('()').split(', ')
out.append((float(a),float(b)))
return out
this should do the job.
I've used safe_eval for jobs like this in the past.
If you're working with a CSV file, and you want more than the "naive" solution which doesn't handle any errors, you're probably best off using the Python's CSV module.
Download PyParsing.
I've worked with it before. You can get some pretty robust parsing behavior out of it, and I think it provides builtins that will handle your entire parsing needs with this sort of thing. Look up commaSeparatedList and nestedExpr.
what's wrong with doing it systematically ? split on ")", then go through the list, remove all "(".
>>> s="(8, 12.25), (13, 15), (16.75, 18.5)"
>>> [ i.replace("(","") for i in s.split(")") ]
['8, 12.25', ', 13, 15', ', 16.75, 18.5', '']
>>> b = [ i.replace("(","") for i in s.split(")") ]
>>> for i in b:
... print i.strip(", ").replace(" ","").split(",")
...
['8', '12.25']
['13', '15']
['16.75', '18.5']
['']
Now you can bring each element into your data structure.
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