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In this guide you will clone or download the Corner Grocer source files, create a small grocery input file, and run both the file-based and database-backed versions of the application from your terminal. By the end you will have a working frequency tracker, a populated SQLite database, and a clear picture of what each menu option does.
1

Download the source files

Grab the four Python files from the downloads/ directory of the repository and place them all in the same working directory on your machine:
your-project/
├── corner_grocer.py
├── grocery_utils.py
├── corner_grocer_main.py
└── db_handler.py
corner_grocer.py and corner_grocer_main.py are the two entry points. Both import grocery_utils; corner_grocer_main.py additionally imports db_handler. Keeping all four files together means Python can resolve every import without any extra configuration.
2

Create an input file

Create a plain-text file called grocery_input.txt in the same directory. Add one item per line — the file below uses real items from the included sample:
Apples
Bananas
Spinach
Potatoes
Tomatoes
Apples
Bananas
Carrots
Onions
Milk
Bread
Eggs
Chicken
Apples
Spinach
Bananas
Rice
Cheese
Oranges
Grapes
Items are normalized to lowercase when they are read, so you can mix capitalisation freely. Blank lines are ignored.For the file-based version (corner_grocer.py), the default input filename is grocery_frequency_input.txt. You can either rename your file or edit the INPUT_FILE constant near the bottom of corner_grocer.py.
3

Run the file-based version

From your project directory, run:
python corner_grocer.py
Corner Grocer reads grocery_frequency_input.txt, builds the frequency map in memory, and drops you into a 7-option interactive menu:
========== Corner Grocer Menu ==========
1. Look up item frequency
2. Print all items and frequencies
3. Print frequency histogram
4. Sort items alphabetically (A–Z)
5. Sort items by frequency (high → low)
6. Search for a specific item
7. Exit program
Enter your choice:
Menu input is validated — entering a letter or a number outside 1–7 prints an error message and re-displays the prompt without crashing.
4

Run the database-backed version

For persistent storage, run the second entry point:
python corner_grocer_main.py
On first launch, db_handler.py automatically creates grocery.db in the working directory and sets up the grocery_frequency table. The program then reads grocery_input.txt, populates the database, and opens a 9-option menu:
Connected to database: grocery.db
Verified or created grocery_frequency table.
Processed input file: grocery_input.txt

========== Corner Grocer Menu ==========
1. Look up item frequency
2. Print all items and frequencies
3. Print frequency histogram
4. Sort items alphabetically (A–Z)
5. Sort items by frequency (high → low)
6. Search for a specific item
7. Save frequency list to frequency_list.dat
8. Save histogram to frequency_histogram.dat
9. Exit program
Enter your choice:
Because counts are stored in SQLite, running the program a second time with the same input file accumulates the new counts rather than resetting them.
5

Try a lookup

At the menu prompt, enter 1 and press Enter. When asked for an item name, type apples:
Enter your choice: 1
Enter item name: apples
apples was purchased 3 time(s).
The lookup normalizes your input to lowercase before querying, so Apples, APPLES, and apples all return the same count. If an item is not in the log, the response is 0 time(s). — no error is raised.

​
What to expect

The table below covers every menu option across both entry points. Options 1–6 behave identically in both programs; options 7–9 are exclusive to corner_grocer_main.py.
OptionLabelDescription
1Look up item frequencyPrompts for an item name and prints how many times it appears in the purchase log. Returns 0 for unknown items.
2Print all items and frequenciesDisplays every tracked item and its count, sorted alphabetically by get_all_frequencies() or print_all_frequencies().
3Print frequency histogramRenders a text bar chart — one * per purchase — for every item, sorted alphabetically.
4Sort items alphabetically (A–Z)Calls grocery_utils.sort_alpha() to print all items in A–Z order with their counts.
5Sort items by frequency (high → low)Calls grocery_utils.sort_by_freq() to rank items from most to least purchased. In the DB version, ties are broken alphabetically by the SQL ORDER BY.
6Search for a specific itemCalls grocery_utils.search_item(), which normalizes the query and either prints the count or Item not found.
7 (DB only)Save frequency list to fileWrites all item names and counts to frequency_list.dat as item count pairs, one per line.
8 (DB only)Save histogram to fileWrites the asterisk histogram (sorted by frequency descending) to frequency_histogram.dat.
7 (file) / 9 (DB)Exit programPrints Goodbye!, exits the menu loop, and — in the DB version — closes the SQLite connection cleanly.
Item names are normalized to lowercase at every entry point, so Apples, apples, and APPLES all count as the same item. This means your input file can use any capitalisation you like, and lookups will always match regardless of how you type them at the prompt.

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