[SOLVED] Cse2050 mod 1 homework – basic python

You’ll write 3 functions in 3 different files (1 each, for a total of 3 functions) for this homework. We provide 1
of the files with skeleton code for the function; you will have to create the other two yourself. Gradescope
will automatically check for correct file names, function names, and docstrings in required functions when
you submit. (Note – every function you write in this class should have a docstring, but gradescope only
automatically checks the functions we explicitly ask for. If you write extra functions, make sure to include
docstrings for them as well).
Neccesary files:
• fizzbuzz.py (provided)
• anagrams.py (not provided)
• letters.py (not provided)
We also provide some files you do not need to submit, but will be helpful for locally testing letters.py:
• frost.txt
• empty_file.txt
Imports
We do not allow imports on any homework or lab assignments, except for those explicitly specified by
that assignment. Due to the ubiquitous nature of the problems we are solving, there are often modules
that trivialize the assignments when imported, so we restrict imports to ensure you’re learning all relevant
techniques.
Do not import any modules except for those you write yourself, or any exceptions below:
• You can import string for Problem 3 – count_letters
Problem 1 – fizzbuzz.py
Write a function fizzbuzz(start, finish) that prints numbers from start to finish. Replace multiples
of 3 with “fizz”, multiples of 5 with “buzz”, and multiples of both with “fizzbuzz”.
Once you have a working algorithm, edit it to also replace numbers that contain 3 or 5 (e.g. 13, 52) with
“fizz”, “buzz”, or “fizzbuzz”, as appropriate.
>>> fizzbuzz(1, 15)
1
2
fizz
4
buzz
fizz
7
8
fizz
buzz
11
fizz
1
fizz
14
fizzbuzz
Problem 2 – anagrams.py
Write a function is_anagram(word1, word2) that compares two strings and returns a boolean denoting
whether they are anagrams.
>>> is_anagram(‘rat’, ‘tar’)
True
>>> is_anagram(‘rat’, ‘hat’)
False
>>> is_anagram(‘meat’, ‘team’)
True
Problem 3 – letters.py
Write a Python function count_letters(file) for counting letters in a text file.
• Input: name of file relative to the present working directory pwd (see below), e.g. count_letters(‘frost.txt’)
if ‘frost.txt’ is in the pwd
• Output: return the dictionary of letter:count pairs. Only include letters present in the file.
• Use a dictionary to hold a mapping between a letter and its number of occurrences.
• Ignore characters and symbols that are not standard ascii characters (only use characters that appear
in string.ascii_lowercase)
• Ignore case; e.g. consider ‘Treat’ as having 2 ‘t’s instead of 1 T and 1 t.
• Reading files – You can use open to open a file. It creates an iterator that goes through the file, line
by line. The example below shows how to iterate over the provided file frost.txt, printing every line:
>>> f = open(‘frost.txt’)
>>> for line in f:
… print(line, end=”)
…
Fire and Ice
Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
-Robert Frost
2
>>> f.close()
Hints
• frost.txt needs to be in your present working directory (pwd) for this to work. For instance, if your
directory sturcure looks like this:
cse2050/
|-homework/
| |homework1/
| | |-frost.txt
| | |-count_letters.py
| |homework2/
| …
|-labs/
| |-lab1/
| | |-lab1.py
| |-lab2/
| …
there are a few directories we could be in: cse2050/, homework/, homework1/, homework2/, labs/,
lab1/, and lab2/ are all valid directories in the tree pictured. Make sure your terminal is in the
directory containing frost.txt, or you’ll get an error – this commonly happend when VSCode is open
in a high level directory, like cse2050/, and you click the “play” button to run a python script in a
nested directory:
[jas14034@jas14034-vm cse2050]$ pwd
/home/jas14034/cse2050
[jas14034@jas14034-vm cse2050]$ /bin/python3 /home/jas14034/cse2050/homework/homewor…
…k1/count_letters.py
Traceback (most recent call last):
File “/home/jas14034/cse2050/homework/homework1/count_letters.py”, line 1, in <m…
…odule>
f = open(‘./frost.txt’)
FileNotFoundError: [Errno 2] No such file or directory: ‘./frost.txt’
My present working directory (pwd) is cse2050/, so my terminal cannot see frost.txt. It is able to
find letters.py because VSCode supplies the absolute path (home/jas14034/…) to that file. An
easy fix is to move into the directory containing the python script and text file you are interested in,
then running your script with python3 from that directory: (use dir instead of cd and python instead
of python3 on windows):
[jas14034@jas14034-vm cse2050]$ cd homework/homework1/
[jas14034@jas14034-vm homework1]$ pwd
/home/jas14034/cse2050/homework/homework1
[jas14034@jas14034-vm homework1]$ python3 ./count_letters.py
Fire and Ice
Some say the world will end in fire,
Some say in ice.
3
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
-Robert Frost
Grading
Most of the functionality will be auto-graded. We will manually grade for structure and readability – ensure
that:
• Every function has a docstring (more info)
• Code is well commented – you don’t need a comment on every line, but don’t assume because you know
what something does that a stranger (or you in two months) will understand it.
• You use consistent variable naming conventions (see the Python style guide)
Submitting
Submit the following files:
• fizzbuzz.py
• anagrams.py
• letters.py
Students must submit to Gradescope individually by the due date (typically Tuesday at 11:59 pm EST) to
receive credit.
Challenges
Hankering for more coding practice? We’ll occasionally provide stretch-goals or more difficult variants of
homework problems. These are not for extra credit and are not required, they’re just here in case you want
to dive a bit deeper into the content.
Problem 3 Challenge
Write a Python function letter_frequency(dict_letters) for finding the frequency of each letter in a
dictionary.
• As input, take a dictionary of letter:count pairs (output of the previous function)
• Find the relative frequency of each letter (the ratio between the number of its occurrences and the total
number of letters)
• Return the new letter:frequency dictionary.
• In Python, passing mutable objects like dictionaries can be considered as a call by reference – if you
modify the dictionary passed to this function, the original dictionary will also be modified! In this
problem, that’s a bad thing – don’t modify the original dictionary. Instead, create a new dictionary for
holding frequencies.
4
• Example:
>>> counts = letter_count(‘frost.txt’)
>>> print(counts)
{`a`: 13, `b`: 2, (24 letter:count pairs omitted)}
>>> freqs = letter_frequency(counts)
{‘a’: 0.06190476190476191, ‘b’: 0.009523809523809525, (24 pairs omitted)}
Next, make a new file highest_freq.py. Import the functions you wrote in Part 1 and use them to implement
a new function highest_freq(). highest_freq(file) should find the letter that has the highest frequency
in a given txt file.
• Return letter and its frequency. Example (‘e’, 0.12451162240025257)
• Use the imported functions from letters.py to do this
• Test your code with assert statements
• Example:
>>> ltr, freq = highest_freq(“frost.txt”)
>>> print(ltr, freq)
e 0.10952380952380952