Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/apursley2012/corner-grocer/llms.txt

Use this file to discover all available pages before exploring further.

Corner Grocer can save its frequency data to disk at any time during a session. The database-backed version (corner_grocer_main.py) provides two dedicated export options in its menu: one that writes a plain frequency list and one that writes an asterisk histogram. These exports give you a persistent snapshot of the current purchase data that can be archived, shared, or opened in any text editor — without ending your session or losing any data from the running application.

​
Frequency list export

Menu option 7 in corner_grocer_main.py writes every item and its purchase count to frequency_list.dat, one entry per line: 
elif choice == 7:
    try:
        with open("frequency_list.dat", "w", encoding="utf-8") as f:
            for item, freq in app.get_all_frequencies().items():
                f.write(f"{item} {freq}\n")
        print("Saved to frequency_list.dat")
    except Exception as e:
        print(f"Failed to save frequency list: {e}")
app.get_all_frequencies() returns a dictionary of all item names and their counts from the database. The loop writes each (item, freq) pair as item count — the item name, a single space, and the integer count — followed by a newline. The file is opened in "w" (write) mode with UTF-8 encoding so multi-character item names are handled correctly. Sample frequency_list.dat content: 
apples 4
avocado 1
bananas 4
beef 1
bell peppers 1
bread 3
broccoli 1
butter 1
carrots 3
cheese 2
chicken 2
corn 1
cucumber 1
eggs 1
fish 1
flour 1
garlic 1
ginger 1
grapes 1
green beans 1
herbs 1
lemons 1
lettuce 1
limes 1
mango 1
milk 3
nuts 1
oil 1
onions 2
oranges 1
pasta 1
peas 1
pepper 1
pineapple 1
potatoes 2
rice 2
salt 1
seeds 1
spinach 3
strawberries 1
sugar 1
tomatoes 2
watermelon 1
yogurt 1

​
Histogram export

Menu option 8 writes a visual asterisk histogram to frequency_histogram.dat. Items are retrieved sorted by count (highest first) via app.get_frequencies_sorted_by_count(): 
elif choice == 8:
    try:
        with open("frequency_histogram.dat", "w", encoding="utf-8") as f:
            for item, freq in app.get_frequencies_sorted_by_count().items():
                f.write(f"{item}: {'*' * freq}\n")
        print("Saved to frequency_histogram.dat")
    except Exception as e:
        print(f"Failed to save histogram: {e}")
The expression '*' * freq repeats the asterisk character exactly freq times, producing a bar whose length directly represents the item’s purchase count. Items are ordered by descending frequency so the most-purchased items appear at the top of the file. Sample frequency_histogram.dat content: 
apples: ****
bananas: ****
bread: ***
carrots: ***
milk: ***
spinach: ***
cheese: **
chicken: **
onions: **
potatoes: **
rice: **
tomatoes: **
avocado: *
beef: *
bell peppers: *
broccoli: *
butter: *
corn: *
cucumber: *
eggs: *
fish: *
flour: *
garlic: *
ginger: *
grapes: *
green beans: *
herbs: *
lemons: *
lettuce: *
limes: *
mango: *
nuts: *
oil: *
oranges: *
pasta: *
peas: *
pepper: *
pineapple: *
salt: *
seeds: *
strawberries: *
sugar: *
watermelon: *
yogurt: *

​
File-based backup (Enhancement One)

The original Enhancement One (corner_grocer.py) tracks frequency using an in-memory defaultdict(int) rather than a database. Its menu offers 7 options (1–7, where 7 is Exit), so it does not include dedicated save menu entries. If you need persistent output from the file-based version, you can redirect terminal output to a file when running it from the command line, or add export logic modeled on the corner_grocer_main.py pattern shown above. The database-backed version (corner_grocer_main.py) introduced the dedicated export options as part of its expanded 9-option menu, making on-demand saves available without leaving the application.

​
Output file locations

Both .dat files are written to the current working directory — the directory from which you launched the Python script. If you run the application from /home/user/corner-grocer/, both files will appear there: 
/home/user/corner-grocer/
├── corner_grocer_main.py
├── grocery_utils.py
├── db_handler.py
├── grocery.db
├── grocery_input.txt
├── frequency_list.dat        ← created by option 7
└── frequency_histogram.dat   ← created by option 8
After a successful save, the terminal confirms the operation: 
Saved to frequency_list.dat
or 
Saved to frequency_histogram.dat
If the write fails (for example, due to a permissions error), the except Exception as e block catches the error and prints the reason without crashing the application, so the menu remains available.
Exporting does not clear or reset any data. The .dat files are a point-in-time snapshot of the frequency data currently held in the database. You can continue using the application normally after exporting — adding items, sorting, searching — and export again at any time to capture an updated snapshot.
If frequency_list.dat or frequency_histogram.dat already exists in the current working directory when you trigger an export, it will be silently overwritten. Python opens the file in "w" (write) mode, which truncates any existing content before writing. There is no prompt and no backup copy is made. If you need to preserve a previous export, rename or move the file before running the export again.

Build docs developers (and LLMs) love

Get started for freeTalk to us