using python to interact with the operating system week 3 answers

Practice Quiz: Regular Expressions

1. When using regular expressions, which of the following expressions uses a reserved character that can represent any single character?

  • re.findall(fu$, text)
  • re.findall(f*n, text)
  • re.findall(^un, text)
  • re.findall(f.n, text)

2. Which of the following is NOT a function of the Python regex module?

  • re.grep()
  • re.match()
  • re.search()
  • re.findall()

3. The circumflex [^] and the dollar sign [$] are anchor characters. What do these anchor characters do in regex?

  • Match the start and end of a word.
  • Match the start and end of a line
  • Exclude everything between two anchor characters
  • Represent any number and any letter character, respectively

4. When using regex, some characters represent particular types of characters. Some examples are the dollar sign, the circumflex, and the dot wildcard. What are these characters collectively known as?

  • Special characters
  • Anchor characters
  • Literal characters
  • Wildcard characters

5. What is grep?

  • An operating system
  • A command for parsing strings in Python
  • A command-line regex tool
  • A type of special character

6. The check_web_address function checks if the text passed qualifies as a top-level web address, meaning that it contains alphanumeric characters (which includes letters, numbers, and underscores), as well as periods, dashes, and a plus sign, followed by a period and a character-only top-level domain such as ".com", ".info", ".edu", etc. Fill in the regular expression to do that, using escape characters, wildcards, repetition qualifiers, beginning and end-of-line characters, and character classes.

import re
def check_web_address(text):
pattern = ___
result = re.search(pattern, text)
return result != None

print(check_web_address("gmail.com")) # True
print(check_web_address("www@google")) # False
print(check_web_address("www.Coursera.org")) # True
print(check_web_address("web-address.com/homepage")) # False
print(check_web_address("My_Favorite-Blog.US")) # True

  • pattern = r”^\w.*\.[a-zA-Z]*$”

7. The check_time function checks for the time format of a 12-hour clock, as follows: the hour is between 1 and 12, with no leading zero, followed by a colon, then minutes between 00 and 59, then an optional space, and then AM or PM, in upper or lower case. Fill in the regular expression to do that. How many of the concepts that you just learned can you use here?

import re
def check_time(text):
pattern = ___
result = re.search(pattern, text)
return result != None

print(check_time("12:45pm")) # True
print(check_time("9:59 AM")) # True
print(check_time("6:60am")) # False
print(check_time("five o'clock")) # False

  • pattern = r”^(1[012]|[1-9]):[0-5][0-9] ?[APap][Mm]$”

8. The contains_acronym function checks the text for the presence of 2 or more characters or digits surrounded by parentheses, with at least the first character in uppercase (if it's a letter), returning True if the condition is met, or False otherwise. For example, "Instant messaging (IM) is a set of communication technologies used for text-based communication" should return True since (IM) satisfies the match conditions." Fill in the regular expression in this function:

import re
def contains_acronym(text):
pattern = ___
result = re.search(pattern, text)
return result != None

print(contains_acronym("Instant messaging (IM) is a set of communication technologies used for text-based communication")) # True
print(contains_acronym("American Standard Code for Information Interchange (ASCII) is a character encoding standard for electronic communication")) # True
print(contains_acronym("Please do NOT enter without permission!")) # False
print(contains_acronym("PostScript is a fourth-generation programming language (4GL)")) # True
print(contains_acronym("Have fun using a self-contained underwater breathing apparatus (Scuba)!")) # True

  • pattern = r”\(\w.*\w\)”
     

9. What does the "r" before the pattern string in re.search(r"Py.*n", sample.txt) indicate?

  • Raw strings
  • Regex
  • Repeat
  • Result

10. What does the plus character [+] do in regex?

  • Matches plus sign characters
  • Matches one or more occurrences of the character before it
  • Matches the end of a string
  • Matches the character before the  [+] only if there is more than one

11. Fill in the code to check if the text passed includes a possible U.S. zip code, formatted as follows: exactly 5 digits, and sometimes, but not always, followed by a dash with 4 more digits. The zip code needs to be preceded by at least one space, and cannot be at the start of the text.

import re
def check_zip_code (text):
result = re.search(r"___", text)
return result != None

print(check_zip_code("The zip codes for New York are 10001 thru 11104.")) # True
print(check_zip_code("90210 is a TV show")) # False
print(check_zip_code("Their address is: 123 Main Street, Anytown, AZ 85258-0001.")) # True
print(check_zip_code("The Parliament of Canada is at 111 Wellington St, Ottawa, ON K1A0A9.")) # False

  • result = re.search(r”(?<!^)\s\d{5}(-\d{4})?”, text)

12. We're working with a CSV file, which contains employee information. Each record has a name field, followed by a phone number field, and a role field. The phone number field contains U.S. phone numbers, and needs to be modified to the international format, with "+1-" in front of the phone number. Fill in the regular expression, using groups, to use the transform_record function to do that.

import re
def transform_record(record):
new_record = re.sub(___)
return new_record

print(transform_record("Sabrina Green,802-867-5309,System Administrator"))
# Sabrina Green,+1-802-867-5309,System Administrator

print(transform_record("Eli Jones,684-3481127,IT specialist"))
# Eli Jones,+1-684-3481127,IT specialist

print(transform_record("Melody Daniels,846-687-7436,Programmer"))
# Melody Daniels,+1-846-687-7436,Programmer

print(transform_record("Charlie Rivera,698-746-3357,Web Developer"))
# Charlie Rivera,+1-698-746-3357,Web Developer

  • new_record = re.sub(r”,([\d-]+)”,r”,+1-\1″ ,record)
     

13. The multi_vowel_words function returns all words with 3 or more consecutive vowels (a, e, i, o, u). Fill in the regular expression to do that.

import re
def multi_vowel_words(text):
pattern = ___
result = re.findall(pattern, text)
return result

print(multi_vowel_words("Life is beautiful"))
# ['beautiful']

print(multi_vowel_words("Obviously, the queen is courageous and gracious."))
# ['Obviously', 'queen', 'courageous', 'gracious']

print(multi_vowel_words("The rambunctious children had to sit quietly and await their delicious dinner."))
# ['rambunctious', 'quietly', 'delicious']

print(multi_vowel_words("The order of a data queue is First In First Out (FIFO)"))
# ['queue']

print(multi_vowel_words("Hello world!"))
# []

  • pattern = r”\b\w*[aeiou]{3,}\w*\b”
     

14. When capturing regex groups, what datatype does the groups method return?

  • A string
  • A tuple
  • A list
  • A float

15. The transform_comments function converts comments in a Python script into those usable by a C compiler. This means looking for text that begins with a hash mark (#) and replacing it with double slashes (//), which is the C single-line comment indicator. For the purpose of this exercise, we'll ignore the possibility of a hash mark embedded inside of a Python command, and assume that it's only used to indicate a comment. We also want to treat repetitive hash marks (##), (###), etc., as a single comment indicator, to be replaced with just (//) and not (#//) or (//#). Fill in the parameters of the substitution method to complete this function:

import re
def transform_comments(line_of_code):
result = re.sub(___)
return result

print(transform_comments("### Start of program"))
# Should be "// Start of program"
print(transform_comments(" number = 0 ## Initialize the variable"))
# Should be " number = 0 // Initialize the variable"
print(transform_comments(" number += 1 # Increment the variable"))
# Should be " number += 1 // Increment the variable"
print(transform_comments(" return(number)"))
# Should be " return(number)"

  • result = re.sub(r”#+”, r”//”, line_of_code)
     

16. The convert_phone_number function checks for a U.S. phone number format: XXX-XXX-XXXX (3 digits followed by a dash, 3 more digits followed by a dash, and 4 digits), and converts it to a more formal format that looks like this: (XXX) XXX-XXXX. Fill in the regular expression to complete this function.

import re
def convert_phone_number(phone):
result = re.sub(___)
return result

print(convert_phone_number("My number is 212-345-9999.")) # My number is (212) 345-9999.
print(convert_phone_number("Please call 888-555-1234")) # Please call (888) 555-1234
print(convert_phone_number("123-123-12345")) # 123-123-12345
print(convert_phone_number("Phone number of Buckingham Palace is +44 303 123 7300")) # Phone number of Buckingham Palace is +44 303 123 7300

  • result = re.sub(r”\b(\d{3})-(\d{3})-(\d{4})\b”, r”(\1) \2-\3″, phone)
     

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