Python read in string from file and split it into values [closed]

Answer 1

Use open(file, mode) for files. The mode is a variant of 'r' for read, 'w' for write, and possibly 'b' appended (e.g., 'rb') to open binary files. See the link below.

Use open with readline() or readlines(). The former will return a line at a time, while the latter returns a list of the lines.

Use split(delimiter) to split on the comma.

Lastly, you need to cast each item to an integer: int(foo). You'll probably want to surround your cast with a try block followed by except ValueError as in the link below.

You can also use 'multiple assignment' to assign a and b at once:

>>>a, b = map(int, "2342342,2234234".split(","))  
>>>print a  
2342342
>>>type(a)  
<type 'int'>

python io docs

python casting

Answer 2

Something like this - for each line read into string variable a:

>>> a = "123,456"
>>> b = a.split(",")
>>> b
['123', '456']
>>> c = [int(e) for e in b]
>>> c
[123, 456]
>>> x, y = c
>>> x
123
>>> y
456

Now you can do what is necessary with x and y as assigned, which are integers.

Answer 3

>>> [[int(i) for i in line.strip().split(',')] for line in open('input.txt').readlines()]
[[995957, 16833579], [995959, 16777241], [995960, 16829368], [995961, 50431654]]

Answer 4

I would do something like:

filename = "mynumbers.txt"
mynumbers = []
with open(filename) as f:
    for line in f:
        mynumbers.append([int(n) for n in line.strip().split(',')])
for pair in mynumbers:
    try:
        x,y = pair[0],pair[1]
        # Do Something with x and y
    except IndexError:
        print "A line in the file doesn't have enough entries."

The with open is recommended in http://docs.python.org/tutorial/inputoutput.html since it makes sure files are closed correctly even if an exception is raised during the processing.