Question

1.

Define the draw_histogram() function which is passed a Python dictionary as a parameter. The keys of the dictionary are single letters and the corresponding values are integers, e.g., {'b': 5, 'a': 6, 'c': 3}. For each key:value pair in the dictionary the function prints the key, followed by ": ", followed by a series of stars. The number of stars printed is given by the value corresponding to the key. The keys are printed in alphabetical order. Note that the key is not printed if the corresponding value is a number less than 1.

For example, the following code:

print("1.")

draw_histogram({'a': 2, 'c': 7, 'b': 5})

print()

print("2.")

draw_histogram({'a': 0, 'c': 5, 'b': 7, 'f': 0})

prints the following:

1.

a: **

b: *****

c: *******

2.

b: *******

c: *****

2.

Define the get_last_three_letters_dict() function which is passed a string of text as a parameter. The function first converts the parameter string to lower case and then returns a dictionary object which has:

• keys which are the last three letters of any words in the parameter string of text with length greater than 2, and,

• corresponding values which are the number of words in the parameter string of text which end with these last three letters.

Notes:

• the testing code removes any pairs in the resulting dictionary where the last three letters occur just the once in the parameter string of text.

• the testing code makes use of the print_dict_in_key_order(a_dict) which prints the dictionary pairs in sorted key order.

For example, the code:

text = ' "west best worst first tapping snapping in a pest the straining singing forest living'

a_dict = get_last_three_letters_dict(text)

remove_less_than_2(a_dict)

print("1.")

print_dict_in_key_order(a_dict)

print()

text = 'Kublai Khan does not necessarily believe everything Marco Polo says when he describes the cities visited on his expeditions but the emperor of the Tartars does continue listening to the young Venetian with greater attention and curiosity than he shows any other messenger or explorer of his'

a_dict = get_last_three_letters_dict(text)

remove_less_than_2(a_dict)

print("2.")

print_dict_in_key_order(a_dict)

prints:

1.

est : 4

ing : 5

rst : 2

2.

han : 2

his : 2

ing : 2

oes : 2

the : 4

Answer 1

def draw_histogram(data):

s = "" # to store the result

#use sorted() to sort dictionary by keys

#loop through all the keys in the dictionary

for x in sorted(data) :

   #store the keys first if freq is non 0

   if(data[x] > 0):

     s = s + str(x) + ": "

     #store the required number of *

     for i in range(data[x]):

       s = s + "*"

     #Add new line

     s = s + " "

#print all data

print(s)

   

return

print("1.")

draw_histogram({'a': 2, 'c': 7, 'b': 5})

print()

print("2.")

draw_histogram({'a': 0, 'c': 5, 'b': 7, 'f': 0})