Function that takes directory of .txt file and returns a dictionary based on set parameters?

I want to make a function that takes the directory of a .txt file as an input and returns a dictionary based on specific parameters. If the .txt file is empty, then the function will return nothing. When writing this function, I request that no imports, no list comprehension, and only for/while and if statements are used.

This is for the sake of the content I am learning right now, and I would like to be able to learn and interpret the function step-by-step.

An example of a .txt file is below. The amount of lines can vary but every line is formatted such that they appear in the order:

word + a string of 3 numbers connected by commas.

terra,4,5,6

cloud,5,6,7

squall,6,0,8

terra,4,5,8

cloud,6,5,7

First I would like to break down the steps of the function

Each component of the string that is separated by a comma serves a specific purpose:

1. The last number in the string will be subtracted by the second to last number in a string to form a value in the dictionary.

for example, the last two characters of terra,4,5,6 will be subtracted to form a value of [1] in the dictionary

2. The alphabetical words will form the keys of the dictionary. If there are multiple entries of the same word in a .txt file then a single key will be formed and it will contain all the values of the duplicate keys.

for example, terra,4,5,6 , terra,4,4,6 , and terra,4,4,7 will output ('terra', 4):[1,2,3] as a key and value respectively.

3. However, in order for a key to be marked as a duplicate, the first values of the keys must be the same. If they are not, then they will be separate values.

For example, terra,4,5,6 and terra,5,4,6 will appear separately from eachother in the dictionary as ('terra', 4):[1] and ('terra', 5):[2] respectively.

Example input

if we use the example .txt file mentioned above, the input should look like create_dict("***files/example.txt") and should ouput a dictionary {('terra', 4):[1,3],('cloud', 5):[1],('squall', 6):[8],('cloud', 6):[2]}. I will add a link to the .txt file for the sake of recreating this example. (note that *** are placeholders for the rest of the directory)

What I'm Trying:

testfiles = (open("**files/example.txt").read()).split('\n')
int_list = []
alpha_list = []
for values in testfiles:
    ao = values.split(',') #returns only a portion of the list. why?
for values in ao:
    if values.isnumeric():
        int_list.append(values) #retrives list of ints from list
for values in ao:
    if values.isalpha():
        alpha_list.append(values) #retrieves a list of words
{((alpha_list[0]), int(int_list[0])):(int(int_list[2])-(int(int_list[1])))} #each line will always have 3 number values so I used index

this returns {('squall', 6): 1} which is mainly just a proof of concept and not a solution to the function. I wanted to see if it was possible to use the numbers and words I found in int_list and alpha_list using indexes to generate entries in the dictionary. If possible, the same could be applied to the rest of the strings in the .txt file.

Your input is in CSV format. You really should be using one of these

• https://docs.python.org/3/library/csv.html#csv.reader
• https://docs.python.org/3/library/csv.html#csv.DictReader

since "odd" characters within a comma-separated field are non-trivial to handle. Better to let the library worry about such details.

Using defaultdict(list) is the most natural way, the most readable way, to implement your dup key requirement. https://docs.python.org/3/library/collections.html#collections.defaultdict

I know, I know, "no import"; now on to a variant solution.

---

d = {}
with open('example.txt') as f:
    for line in f:
        word, nums = line.split(',', maxsplit=1)
        a, b, c = map(int, nums.split(','))
        delta = c - b
        key = (word, a)
        if key not in d:
            d[key] = []
        d[key].append(delta)
return d