M03 - Open and Read Files

Question 1

Text File

Answer 1

• Can be opened in a text editor like VS Code or Notepad
• CSV is a text file
• Data in text file is encoded as text using ASCII or Unicode

Question 2

Binary File

Answer 2

• Contains data that has not been converted to text

- Cannot be opened with a text editor

Question 3

General format for opening a file:

Answer 3

file_variable = open(‘filename’, ‘mode’)

Question 4

Mode arguments in open( )

Answer 4

• ‘r’ opens a file to be read
• ‘w’ opens a file to write to it. This will overwrite an existing file and create a file if one does not already exist
• ‘x’ opens a file for exclusive creation. If it does not exist, it will not create one
• ‘a’ opens a file to append data to an existing file. If a file does not exist, it creates one, if a file has been created the data will be added to the file
• ’+’ opens a file for reading and writing

Question 5

Open file, to read, w/ direct path

Answer 5

# Assign a variable for the file to load and the path
file_to_load = 'file\path.ext'

# Open the file and read the file
file_variable = open(file_to_load , 'r')

Question 6

Close a file

Answer 6

file_variable.close( )

Question 7

Important notes about closing a file

Answer 7

• When you read data from a file and it is not closed at the end, you can lose some of the data
• When you write data to a file, the data is not stored in the file at first. It’s written to a buffer in the memory and may be overwritten later if the file is not closed. Once closed, the data is stored

Question 8

with statement

Answer 8

• replaces need to open( ) and close( ) every time
• with opens the file and ensures proper acquisition or release of any data without having to close the file, ensuring the data isn’t lost or corrupted

Question 9

with statement syntax

Answer 9

with open(filename) as file_variable:

-file_variable is used to reference the file object through the script

Question 10

with - open and print file data

Answer 10

# Assign a variable for the file to load and the path
file_to_load = 'file\path.ext'

# Open the file
with open(file_to_load) as file_data :
(tab) print(file_data)

Question 11

If we don’t know the direct path to the file, use which module?

Answer 11

os (operating system)

import os

Question 12

os.path allows

Answer 12

• Us to access files on different operating systems like macOS and Windows
• Contains several useful functions to make it easier to join a path

Question 13

os.path.join( )

Answer 13

-Joins our files path components together when they are provided as separate strings; then returns a direct path with the appropriate operating system separator (\ for windows or / for mac)

Question 14

Chaining

Answer 14

• Programmatic style that is used for making multiple method calls on the same object
• Common practice to make code look clean/concise

Question 15

Indirect Path syntax

Answer 15

file_to_load = os.path.join(“FileName” , “file.ext”)