How to read in one character at a time from a file in python?

Question

I want to read in a list of numbers from a file as chars one char at a time to check what that char is, whether it is a digit, a period, a + or -, an e or E, or some other c

Answer 1

Here is a technique to make a one-character-at-a-time file iterator:

from functools import partial

with open("file.data") as f:
    for char in iter(partial(f.read, 1), ''):
        # now do something interesting with the characters
        ...

• The with-statement opens the file and unconditionally closes it when you're finished.
• The usual way to read one character is f.read(1).
• The partial creates a function of zero arguments by always calling f.read with an argument of 1.
• The two argument form of iter() creates an iterator that loops until you see the empty-string end-of-file marker.