Start with the following Python code. alphabet = "abcdefghijklmnopqrstuvwxyz" test_dups = ["zzz","dog","bookkeeper","subdermatog
lyphic","subdermatoglyphics"] test_miss = ["zzz","subdermatoglyphic","the quick brown fox jumps over the lazy dog"] # From Section 11.2 of: # Downey, A. (2015). Think Python: How to think like a computer scientist. Needham, Massachusetts: Green Tree Press. def histogram(s): d = dict() for c in s: if c not in d: d[c] = 1 else: d[c] += 1 return d Copy the code above into your program but write all the other code for this assignment yourself. Do not copy any code from another source. Part 1 Write a function called has_duplicates that takes a string parameter and returns True if the string has any repeated characters. Otherwise, it should return False. Implement has_duplicates by creating a histogram using the histogram function above. Do not use any of the implementations of has_duplicates that are given in your textbook. Instead, your implementation should use the counts in the histogram to decide if there are any duplicates. Write a loop over the strings in the provided test_dups list. Print each string in the list and whether or not it has any duplicates based on the return value of has_duplicates for that string. For example, the output for "aaa" and "abc" would be the following. aaa has duplicates abc has no duplicates Print a line like one of the above for each of the strings in test_dups. Part 2 Write a function called missing_letters that takes a string parameter and returns a new string with all the letters of the alphabet that are not in the argument string. The letters in the returned string should be in alphabetical order. Your implementation should use a histogram from the histogram function. It should also use the global variable alphabet. It should use this global variable directly, not through an argument or a local copy. It should loop over the letters in alphabet to determine which are missing from the input parameter. The function missing_letters should combine the list of missing letters into a string and return that string. Write a loop over the strings in list test_miss and call missing_letters with each string. Print a line for each string listing the missing letters. For example, for the string "aaa", the output should be the following. aaa is missing letters bcdefghijklmnopqrstuvwxyz If the string has all the letters in alphabet, the output should say it uses all the letters. For example, the output for the string alphabet itself would be the following. abcdefghijklmnopqrstuvwxyz uses all the letters Print a line like one of the above for each of the strings in test_miss. Submit your Python program. It should include the following. The provided code for alphabet, test_dups, test_miss, and histogram. Your implementation of the has_duplicates function. A loop that outputs duplicate information for each string in test_dups. Your implementation of the missing_letters function. A loop that outputs missing letters for each string in test_miss. Also submit the output from running your program. Your submission will be assessed using the following Aspects. Does the program include a function called has_duplicates that takes a string parameter and returns a boolean? Does the has_duplicates function call the histogram function? Does the program include a loop over the strings in test_dups that calls has_duplicate on each string? Does the program correctly identify whether each string in test_dups has duplicates? Does the program include a function called missing_letters that takes a string parameter and returns a string parameter? Does the missing_letters function call the histogram function? Does the missing_letters function use the alphabet global variable directly? Does the program include a loop over the strings in test_miss that calls missing_letters on each string? Does the program correctly identify the missing letters for each string in test_miss, including each string that "uses all the letters"?
1 answer:
Answer:
alphabet = "abcdefghijklmnopqrstuvwxyz"
test_dups = ["zzz","dog","bookkeeper","subdermatoglyphic","subdermatoglyphics"]
test_miss = ["zzz","subdermatoglyphic","the quick brown fox jumps over the lazy dog"]
# From Section 11.2 of: # Downey, A. (2015). Think Python: How to think like a computer scientist. Needham, Massachusetts: Green Tree Press.
def histogram(s):
d = dict()
for c in s:
if c not in d:
d[c] = 1
else:
d[c] += 1
return d
#Part 1 Construct a function, called has_duplicates, that takes a string argument and returns True if there are any repeating characters present. If not, it should return False.
def has_duplicates(stringP):
dic = histogram(stringP)
for key,value in dic.items():
if value>1:
return True
return False
# Execute has_duplicates by building a histogram using the above histogram function. Implement a loop over the items in the test_dups list.
# Display each string and indicate whether it has duplicates based on the has_duplicates function's result for that string.
# For instance, the expected output for "aaa" and "abc" would be shown below. aaa has duplicates abc has no duplicates Display a similar message for each string within test_dups.
print("***Implementation of has_duplicates function***")
for sTr in test_dups:
if has_duplicates(sTr):
print(sTr+": has duplicates")
else:
print(sTr+": has no duplicates")
#Part 2 Develop a function named missing_letters that takes a string argument and returns a new string containing all alphabet letters absent from the input string.
#The letters in the resultant string should be arranged in alphabetical order. Your implementation must utilize the histogram from the previous function and should reference the global alphabet variable directly.
#It should iterate over the alphabet letters to figure out which are missing from the input string.
#The function missing_letters should merge the list of missing letters into a string and return it.
def missing_letters(sTr):
missingLettersList = []
dic = histogram(sTr)
for l in alphabet:
if l not in dic:
missingLettersList.append(l)
missingLettersList.sort()
return "".join(missingLettersList)
#Iterate over the strings in the test_miss list and invoke missing_letters for each one. Present a line for each string outlining the missing letters.
#For example, for the string "aaa", the output should be as follows. aaa is missing letters bcdefghijklmnopqrstuvwxyz
#Should the string encompass all alphabet letters, the output should indicate that it utilizes all the letters.
#For instance, output for the alphabet string itself would be: abcdefghijklmnopqrstuvwxyz uses all the letters
#Generate a similar line for each item in test_miss.
print("\n***Implementation of missing_letters function***")
for lTm in test_miss:
sTr = missing_letters(lTm.replace(" ",""))
if sTr!="":
print(lTm+" is missing letters "+sTr)
else:
print(lTm +" uses all the letters")
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