Opening Files in Python

Tiffany White,Mon Apr 20 2015

So right now I am learning how to open and read files in Python, which is exercise 15. Apparently, it gets super hard around the 30 exercise mark. I am looking forward to the challenge, however.

So I am working through exercise 15. The text file we are to open and read in python contains some arbitrary text. We are still working with argument variables and the command raw_input(), but we’re throwing in the argv

filename

with another command

open

which just opens the file taking a parameter which returns a value, kind of like raw_input, that you can set to any variable you want, according to pydoc (which is the document system built into python– excellent resource, aside from Dash).

Here is the script I wrote:

from sys import argv
 
script, filename = argv
 
txt = open(filename)
 
print “Here’s your file %r:” % filename
print txt.read()
 
print “Type the filename again:”
file_again = raw_input(“&gt; ”)
 
txt_again = open(file_again)
 
print txt_again.read()

Here is my script with the comments I wrote, an annotation that Zed Shaw encourages.

#Grabs the sys module and the argv variable inside that module
 
from sys import argv
 
#sets the argument variables to script and filemane&lt;/h1&gt;
 
script, filename = argv
 
# when we type the script into the terminal, 
# you have to type in the filename as well that you want to open. 
# This filename must be an arguement variable when you run the python script. 
# txt indicates that it is a txt file. Open(filenmae) calls the argument variable 
# that we specified was ex15_sample.txt 
# and opens it, taking a parameter and returning a value you can set as your own value, 
# much like raw_input
 
txt = open(filename)
 
# this line prints out text and opens an formatter which is the argument variable filename.
 
print “Here’s your file %r:” % filename
 
# here we call a function on the text file which is read(). 
# To give a file a command you use the dot and and function so txt.read() opens the file without getting any parameters.
 
print txt.read()
 
#this line prints this line of text in the script in terminal
 
print “Type the filename again:”
 
# this is another prompt with raw_input 
# and the caret assigned to the variable file_again. 
# You must type in the name of the text file again 
# or python will throw an error
 
file_again = raw_input(“&gt; ”)
 
# this line uses the open command to open the txt file again
 
txt_again = open(file_again)
 
# this line uses the function read() which is part of the command you’re giving the file
txt_again.read(). It will then read and print the contents of the file.
 
print txt_again.read()