"""
Writing data to a file
"""

# note that the command 
file_handle = open('numbers.txt')
# can also be written as:
file_handle = open('numbers.txt', 'r')
# the additional argument tells python that we want to open the file for
# the purpose of reading from it (the mode in which to open the file).
# 'r' is the default mode, so can be omitted. 

# if you want to write to a file simply open it in write mode ('w')
# (it doesn't need to exist beforehand):
file_handle = open('my_new_file.txt', 'w')
file_handle.write('this file now has one line\n')
# note that we needed to explicitly put in a new-line character.
file_handle.write('now it has two lines\n')
# and close the file when done:
file_handle.close()

# If you would like to add stuff to a file, open it in append mode ('a'):
file_handle = open('my_new_file.txt', 'a')
file_handle.write('we just added another line\n')
file_handle.close()

# The write method of a file takes a string as its argument.
# If you want to write a floating point number or integer you need to 
# convert it to a string first using str() or the formatting operator (%):
file_handle = open('my_new_file.txt', 'a')
file_handle.write(str(1.1) + '\n')
file_handle.write('%2.1f %2.1f' % (150.3333, 20.289) + '\n')
file_handle.close()