Opening Files in Python
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(“> ”)
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</h1>
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(“> ”)
# 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()
