Python - list of tuples from file

Question

I have completed some rather intensive calculations, and i was not able to save my results in pickle (recursion depth exceded), so i was forced to print all the data and save it in a text file.

Is there any easy way to now convert my list of tuples in text to well... list of tuples in python? the output looks like this:

[(10, 5), (11, 6), (12, 5), (14, 5), (103360, 7), (16, 6), (102725, 7), (17, 6), (18, 5), (19, 9), (20, 6), ...(it continues for 60MB)]

Use [`ast.literal_eval`](https://docs.python.org/3/library/ast.html#ast.literal_eval) — Patrick Haugh, Nov 02 '17 at 11:08
Possible duplicate of https://stackoverflow.com/questions/1894269/convert-string-representation-of-list-to-list-in-python — FcoRodr, Nov 02 '17 at 11:15
Wait, that data is quite flat. Why would pickle exceed recursion depth for this? Is that data example really representative? — Stefan Pochmann, Nov 02 '17 at 11:22

score 5 · Accepted Answer · answered Nov 02 '17 at 11:09

5

You can use ast.literal_eval():

>>> s = '[(10, 5), (11, 6), (12, 5), (14, 5)]'
>>> res = ast.literal_eval(s)
[(10, 5), (11, 6), (12, 5), (14, 5)]
>>> res[0]
(10, 5)

answered Nov 02 '17 at 11:09

ettanany

15,827
5
37
56

i would have to include the whole data in my source then, no? – KONAKONA Nov 02 '17 at 11:11
@KONAKONA No, you'd read it from whatever file it's been saved to – Patrick Haugh Nov 02 '17 at 11:12
@KONAKONA Do you mean that you want to convert only a subset of your stored data? – ettanany Nov 02 '17 at 11:12
Alright, since it is all in one line, i can just read that line, convert it to string, and use ast.literal_eval(), thank you! – KONAKONA Nov 02 '17 at 11:16

Adirio · Answer 2 · 2017-11-02T11:24:03.153

string = "[(10, 5), (11, 6), (12, 5), (14, 5), (103360, 7), (16, 6), (102725, 7), (17, 6), (18, 5), (19, 9), (20, 6)]" # Read it from the file however you want

values = []
for t in string[1:-1].replace("),", ");").split("; "):
    values.append(tuple(map(int, t[1:-1].split(", "))))

First I remove the start and end square bracket with [1:-1], I replace ), with ); to be able to split by ; so that the it foesn't split by the commas inside the tuples as they are not preceded by a ). Inside the loop I'm using [1:-1] to remove the parenthesis this time and splitting by the commas. The map part is to convert the numeric strs into ints and I'm appending them as a tuple.

Python - list of tuples from file

2 Answers2