Question

In python I have read in a file into a list using file.readlines() , later on after some logic, I would like to put it back together in a string using fileString = ''.join(file), for some reason, even without a print function, it prints the fileString out to the console up to a certain point, then it just stops. It does not run the rest of the program which is not useful for me.

Why does join do this, how do I perhaps pre-allocate how much memory I would like my list/string to use so that it does not stop. Or some other solution too.

Thank you

Answer 1

File is your file pointer in memory. When you attempt to join on it, you don’t actually have a string to work with.

How about this?

with open(file, 'rb') as myfile:
    strings = myfile.readlines()

# do your stuff to strings
filestring = ''.join(strings)

Note that strings is a list of lines like this:

[‘my line\n’, ‘my other line!\n’]

And as such, a large file will require quite a bit of memory. You may be better served by building a mini filter.