Question

I have a text file I would like to read in that contains rows of tuples. Each tuple/row in text is in the form of (‘description string’, [list of integers 1], [list of integers 2]). Where the text file might look something like:

(‘item 1’, [1,2,3,4] , [4,3,2,1])
(‘item 2’, [ ] , [4,3,2,1])
(‘item 3, [1,2] , [ ])

I would like to be able to read each line in from the text file, then place them directly into a function where,

function(string, list1, list2)

I know that each line is read in as a string, but I need to extract this string some how. I have been trying to use a string.split(‘,’), but that comes into problems when I hit the lists. Is there a way to accomplish this or will I have to modify my text files some how?

I also have a text file of a list of tuples that I would like to read in similarly that is in the form of

[(1,2),(3,4),(5,6),…]

that may contain any amount of tuples. I would like to read it in a list and do a for loop for each tuple in the list. I figure these two will use roughly the same process.

Answer 1

What about using eval?

EDIT See @Ignacio’s answer using ast.literal_eval.

>>> c = eval("('item 1', [1,2,3,4] , [4,3,2,1])")
>>> c
('item 1', [1, 2, 3, 4], [4, 3, 2, 1])

I would only recommend doing this if you are 100% sure of the contents of the file.

>>> def myFunc(myString, myList1, myList2):
...     print myString, myList1, myList2
... 
>>> myFunc(*eval("('item 1', [1,2,3,4] , [4,3,2,1])"))
item 1 [1, 2, 3, 4] [4, 3, 2, 1]

See @Ignacio’s answer… much, much safer.

Applying the use of ast would yield:

>>> import ast
>>> def myFunc(myString, myList1, myList2):
...     print myString, myList1, myList2
... 
>>> myFunc(*ast.literal_eval("('item 1', [1,2,3,4] , [4,3,2,1])"))
item 1 [1, 2, 3, 4] [4, 3, 2, 1]