Module 3
In this assignment, you will implement some functions related to strings, lists, sets and tuples. Each function has been defined for you, but without the code. See the docstring in each function for instructions on what the function is supposed to do and how to write the code. It should be clear enough. In some cases, we have provided hints to help you get started.
###########################################################
### EXECUTE THIS CELL BEFORE YOU TO TEST YOUR SOLUTIONS ###
###########################################################
import unittest
from nose.tools import assert_equal, assert_true
import nose.tools
def concatenate(strings):
"""
Concatenates the given list of strings into a single string.
Returns the single string.
If the given list is empty, returns an empty string.
For example:
- If we call concatenate(["a","b","c"]), we'll get "abc" in return
- If we call concatenate([]), we'll get "" in return
Hint(s):
- Remember, you can create a single string from a list of multiple strings by using the join() function
"""
l=""
for a in strings:
l+=a
return l
##########################
### TEST YOUR SOLUTION ###
##########################
lst = ["a","b","c"]
assert_equal("abc",concatenate(lst))
lst = []
assert_equal("",concatenate(lst))
print("Success!")
Success!
def all_but_last(seq):
"""
Returns a new list containing all but the last element in the given list.
If the list is empty, returns None.
For example:
- If we call all_but_last([1,2,3,4,5]), we'll get [1,2,3,4] in return
- If we call all_but_last(["a","d",1,3,4,None]), we'll get ["a","d",1,3,4] in return
- If we call all_but_last([]), we'll get None in return
"""
if seq==[]:
return None
else:
return seq[:-1]
##########################
### TEST YOUR SOLUTION ###
##########################
lst = []
assert_equal(None,all_but_last(lst))
lst = [1,2,3,4,5]
nose.tools.assert_list_equal([1,2,3,4],all_but_last(lst))
lst = ["a","d",1,3,4,None]
nose.tools.assert_list_equal(["a","d",1,3,4],all_but_last(lst))
print("Success!")
Success!
def remove_duplicates(lst):
"""
Returns the given list without duplicates.
The order of the returned list doesn't matter.
For example:
- If we call remove_duplicates([1,2,1,3,4]), we'll get [1,2,3,4] in return
- If we call remove_duplicates([]), we'll get [] in return
Hint(s):
- Remember, you can create a set from a string, which will remove the duplicate elements
"""
o = []
for x in lst:
if x not in o:
o.append(x)
return o
##########################
### TEST YOUR SOLUTION ###
##########################
lst = [1,3,4,3,4,5,2]
nose.tools.assert_count_equal([1,3,4,5,2],remove_duplicates(lst))
lst = []
nose.tools.assert_count_equal([],remove_duplicates(lst))
print("Success!")
Success!
def reverse_word(word):
"""
Reverses the order of the characters in the given word.
For example:
- If we call reverse_word("abcde"), we'll get "edcba" in return
- If we call reverse_word("a b c d e"), we'll get "e d c b a" in return
- If we call reverse_word("a b"), we'll get "b a" in return
- If we call reverse_word(""), we'll get "" in return
Hint(s):
- You can iterate over a word in reverse and access each character
"""
return word[::-1]
##########################
### TEST YOUR SOLUTION ###
##########################
word = "abcdefg"
assert_equal("gfedcba",reverse_word(word))
word = "a b c d e f g"
assert_equal("g f e d c b a",reverse_word(word))
word = "a b"
assert_equal("b a",reverse_word(word))
word = ""
assert_equal("",reverse_word(word))
print("Success!")
Success!
def divisors(n):
"""
Returns a list with all divisors of the given number n.
As a reminder, a divisor is a number that evenly divides another number.
The returned list should include 1 and the given number n itself.
The order of the returned list doesn't matter.
For example:
- If we call divisors(10), we'll get [1,2,5,10] in return
- If we call divisors(1), we'll get [1] in return
"""
out=[]
for i in range(1,n+1):
if(n % i == 0):
out.append(i)
return out
##########################
### TEST YOUR SOLUTION ###
##########################
number = 10
nose.tools.assert_count_equal([1,2,5,10],divisors(number))
number = 1
nose.tools.assert_count_equal([1],divisors(number))
number = 7
nose.tools.assert_count_equal([1,7],divisors(number))
print("Success!")
Success!
def capitalize_or_join_words(sentence):
"""
If the given sentence starts with *, capitalizes the first and last letters of each word in the sentence,
and returns the sentence without *.
Else, joins all the words in the given sentence, separating them with a comma, and returns the result.
For example:
- If we call capitalize_or_join_words("*i love python"), we'll get "I LovE PythoN" in return.
- If we call capitalize_or_join_words("i love python"), we'll get "i,love,python" in return.
- If we call capitalize_or_join_words("i love python "), we'll get "i,love,python" in return.
Hint(s):
- The startswith() function checks whether a string starts with a particualr character
- The capitalize() function capitalizes the first letter of a string
- The upper() function converts all lowercase characters in a string to uppercase
- The join() function creates a single string from a list of multiple strings
"""
if sentence.startswith('*'):
sentence=sentence.title()
words = sentence.replace('*', '').split()
ans=""
for word in words:
ans+=word[:-1] + word[-1].upper() + " "
return ans.strip()
words = sentence.split()
return ','.join(words)
##########################
### TEST YOUR SOLUTION ###
##########################
string = "*i love python"
assert_equal("I LovE PythoN",capitalize_or_join_words(string))
string = "i love python"
assert_equal("i,love,python",capitalize_or_join_words(string))
string = "i love python "
assert_equal("i,love,python",capitalize_or_join_words(string))
print("Success!")
Success!
def move_zero(lst):
"""
Given a list of integers, moves all non-zero numbers to the beginning of the list and
moves all zeros to the end of the list. This function returns nothing and changes the given list itself.
For example:
- After calling move_zero([0,1,0,2,0,3,0,4]), the given list should be [1,2,3,4,0,0,0,0] and the function returns nothing
- After calling move_zero([0,1,2,0,1]), the given list should be [1,2,1,0,0] and the function returns nothing
- After calling move_zero([1,2,3,4,5,6,7,8]), the given list should be [1,2,3,4,5,6,7,8] and the function returns nothing
- After calling move_zero([]), the given list should be [] and the function returns nothing
"""
no_zero = list()
only_zero = list()
for i in lst:
if i != 0:
no_zero.append(i)
else:
only_zero.append(i)
temp = no_zero + only_zero
i = 0
for e in temp:
lst[i] = e
i += 1
##########################
### TEST YOUR SOLUTION ###
##########################
lst = [0,1,0,2,0,3,0,4]
assert_equal(None,move_zero(lst))
nose.tools.assert_list_equal([1,2,3,4,0,0,0,0],lst)
lst = []
move_zero(lst)
nose.tools.assert_list_equal([],lst)
lst = [0,0,0,0,0,0,0,0,0]
move_zero(lst)
nose.tools.assert_list_equal([0,0,0,0,0,0,0,0,0],lst)
lst = [1,2,3,4,5,6,7,8]
move_zero(lst)
nose.tools.assert_list_equal([1,2,3,4,5,6,7,8],lst)
print("Success!")
Success!
def main():
"""
Calls all the functions above to see whether they've been implemented correctly.
"""
# test concatenate
print("test concatenate")
word = concatenate(["b", "e", "a", "t", "l", "e", "s"])
print(word == "beatles")
print("=" * 50)
# test all_but_last
print("test all_but_last")
seq = all_but_last(["john", "paul", "george", "ringo", "tommy"])
print(seq == ["john", "paul", "george", "ringo"])
print("=" * 50)
# test remove_duplicates
print("test remove_duplicates")
res = remove_duplicates([1, 3, 4, 2, 1])
print(res == [1, 3, 4, 2])
print("=" * 50)
# test reverse_word
print("test reverse_word")
res = reverse_word("alphabet")
print(res == "tebahpla")
print("=" * 50)
# test divisors
print("test divisors")
res = divisors(120)
print(set(res) == set([1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120]))
print("=" * 50)
# test capitalize_or_join_words
print("test capitalize_or_join_words")
print("Result for String Start With *: ")
# Should return "I LovE CodinG AnD I'M HavinG FuN"
res = capitalize_or_join_words("*i love coding and i'm having fun")
print(res == "I LovE CodinG AnD I'M HavinG FuN")
print("Result for Other String: ")
# Should print "I,love,coding,and,I'm,having,fun"
res = capitalize_or_join_words("I love coding and I'm having fun")
print(res == "I,love,coding,and,I'm,having,fun")
print("=" * 50)
# test move_zero
print("test move_zero")
lst = [0, 1, 0, 2, 0, 3, 4, 0]
print("Before move,the list looks like\n", lst)
move_zero(lst)
print("After move,the list looks like\n", lst)
print("=" * 50)
#This will automatically run the main function in your program
#Don't change this
if __name__ == '__main__':
main()
