22 September 2020

Accessing Files

open This function returns a file object. The usage is open(file_name, mode), where file_name is the name of a file, and mode is the mode in which you are opening the file.

ModeWhat it means
"r"This opens a file for reading
"b"This opens a file in binary mode. It can be combined with any of the other modes.
"w"This opens a file for writing; if the file exists, it is clobbered, if not, it is automatically created.
"a"This opens a file for appending. Things get written at the end of an existing file.

Get the file sampler.txt on the left and we will play with it.

Get with it!

The Libraries os and os.path

These let you interact with your file system in a more or less platform-independent way.

chdir(path)
getcwd()
os.listdir(,[dirname])
os.remove(file_name)
os.is_dir(file_name)
os.is_file(file_name)

os.path.abspath(path)
os.path.exists(file_name)
os.getsize(file_name)



import sys
donor_file = sys.argv[1]
recipient_file = sys.argv[2]
fp_in = open(donor_file, "r")
fp_out = open(recipient_file, "w")
for line in fp_in:
    fp_out.write(line)
fp_in.close()
fp_out.close()