Practice Quiz: Reading & Writing CSV Files

6. We're working with a list of flowers and some information about each one. The create_file function writes this information to a CSV file. The contents_of_file function reads this file into records and returns the information in a nicely formatted block. Fill in the gaps of the contents_of_file function to turn the data in the CSV file into a dictionary using DictReader.

import os
import csv

# Create a file with data in it
def create_file(filename):
with open(filename, "w") as file:
file.write("name,color,type\n")
file.write("carnation,pink,annual\n")
file.write("daffodil,yellow,perennial\n")
file.write("iris,blue,perennial\n")
file.write("poinsettia,red,perennial\n")
file.write("sunflower,yellow,annual\n")

# Read the file contents and format the information about each row
def contents_of_file(filename):
return_string = ""

# Call the function to create the file
create_file(filename)

# Open the file
with open(filename) as file:
# Read the rows of the file into a dictionary
f = csv.DictReader(file)
# Process each item of the dictionary
for row in f:
return_string += "a {} {} is {}\n".format(row["color"], row["name"], row["type"])
return return_string

#Call the function
print(contents_of_file("flowers.csv"))

  • # Read the file contents and format the information about each row
    def contents_of_file(filename):
    return_string = “”

    # Call the function to create the file
    create_file(filename)

    # Open the file
    with open(filename) as file:
    # Read the rows of the file into a dictionary
    reader = csv.DictReader(file)
    # Process each item of the dictionary
    for row in reader:
    return_string += “a {} {} is {}\n”.format(row[“color”], row[“name”], row[“type”])
    return return_string

7. Using the CSV file of flowers again, fill in the gaps of the contents_of_file function to process the data without turning it into a dictionary. How do you skip over the header record with the field names?

import os
import csv

# Create a file with data in it
def create_file(filename):
with open(filename, "w") as file:
file.write("name,color,type\n")
file.write("carnation,pink,annual\n")
file.write("daffodil,yellow,perennial\n")
file.write("iris,blue,perennial\n")
file.write("poinsettia,red,perennial\n")
file.write("sunflower,yellow,annual\n")

# Read the file contents and format the information about each row
def contents_of_file(filename):
return_string = ""

# Call the function to create the file
create_file(filename)

# Open the file
with open(filename, 'r') as f:
# Read the rows of the file
rows = csv.reader(f)
# Skips the headers
next(rows)
# Process each row
for row in rows:
name, color, typeflower = row
# Format the return string for data rows only
return_string += "a {} {} is {}\n".format(color, name, typeflower)
return return_string

#Call the function
print(contents_of_file("flowers.csv"))

  • import os
    import csv

    # Create a file with data in it
    def create_file(filename):
    withopen(filename, “w”) asfile:
    file.write(“name,color,type\n”)
    file.write(“carnation,pink,annual\n”)
    file.write(“daffodil,yellow,perennial\n”)
    file.write(“iris,blue,perennial\n”)
    file.write(“poinsettia,red,perennial\n”)
    file.write(“sunflower,yellow,annual\n”)

    # Read the file contents and format the information about each row
    def contents_of_file(filename):
    return_string = “”

    # Call the function to create the file
    create_file(filename)

    # Open the file
    withopen(filename, ‘r’) as f:
    # Read the rows of the file
    rows = csv.reader(f)
    # Skip the header row
    next(rows)
    # Process each row
    for row in rows:
    # Extract the values from the row
    name, color, flower_type = row
    # Format the return string for data rows only
    return_string += “a {} {} is {}\n”.format(color, name, flower_type)

    return return_string

    # Call the function
    print(contents_of_file(“flowers.csv”))

8. In order to use the writerows() function of DictWriter() to write a list of dictionaries to each line of a CSV file, what steps should we take? (Check all that apply)

  • Create an instance of the DictWriter() class
  • Write the fieldnames parameter into the first row using writeheader()
  • Open the csv file using with open
  • Import the OS module

9. Which of the following is true about unpacking values into variables when reading rows of a CSV file? (Check all that apply)

  • We need the same amount of variables as there are columns of data in the CSV
  • Rows can be read using both csv.reader and csv.DictReader
  • An instance of the reader class must be created first
  • The CSV file does not have to be explicitly opened

10. If we are analyzing a file's contents to correctly structure its data, what action are we performing on the file?

  • Writing
  • Appending
  • Parsing
  • Reading
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Devendra Kumar

Project Management Apprentice at Google

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