readxy

def read_xy(file):
    """
    Read x and y values from file for each line
    and return a generator.

    The values are yielded like:
    [(x1,y1), (x2, y2), (x3, y3), ...]
    """
    with open(file) as fd:
        # fd is also a line iterator
        for line in fd:
            if not line.strip():
                # skip if line is empty
                continue

            values = line.split()

            if len(values) != 2:
                # skip if 0, 1 or 3+ values in one line
                continue

            try:
                x, y = map(int, values)
            except ValueError:
                # what to do if x or y is not an int?
                # actually skipping
                continue

            # this line could only be reached,
            # if all previous conditions are ok
            yield x, y


if __name__ == "__main__":
    values = read_xy("test.txt")
    # values is a generator
    # values are lazy evaluated (saving memory)

    # trick to transpose an iterable
    x, y = zip(*values)

    print(f"X: {x}\nY: {y}")