How can I convert "[(5, 2), (1,3), (4,5)]" into a list of tuples
[(5, 2), (1,3), (4,5)]
I am using planetlab shell that does not support "import ast". So I am unable to use it.
3 Answers
If ast.literal_eval is unavailable, you can use the (unsafe!) eval:
>>> s = "[(5, 2), (1,3), (4,5)]"
>>> eval(s)
[(5, 2), (1, 3), (4, 5)]
However, you should really overthink your serialization format. If you're transferring data between Python applications and need the distinction between tuples and lists, use pickle. Otherwise, use JSON.
2 Comments
Slim_user71169
I see if s = "[('a', 2), ('b',3), ('c',5)]" result is [(a, 2), (b, 3), (c, 5)]
If you don't trust the source of the string enough to use eval, then use re.
import re
tuple_rx = re.compile("\((\d+),\s*(\d+)\)")
result = []
for match in tuple_rx.finditer("[(5, 2), (1,3), (4,5)]"):
result.append((int(match.group(1)), int(match.group(2))))
The code above is very straightforward and only works with 2-tuples of integers. If you want to parse more complex structures, you're better off with a proper parser.
Comments
'join' replace following characters '()[] ' and creates string of comma separated numbers
5,2,1,3,4,5
'split' splits that string on ',' and creates list strings
['5','2','1','3','4','5']
'iter' creates iterator that will go over list of elements
and the last line uses a list comprehension using 'zip' to group together two numbers
it = iter("".join(c for c in data if c not in "()[] ").split(","))
result = [(int(x), int(y)) for x, y in zip(it, it)]
>>> [(5, 2), (1, 3), (4, 5)]
ast.literal_evalevalwon't help you?