group_dict_by_key

Module Name: Zeta.Utils

Group dictionary keys group_dict_by_key based on a condition function

The group_dict_by_key function in Zeta.Utils is a utility function that facilitates grouping keys of a dictionary based on a specified condition. The condition is defined by a custom function.

The function returns two dictionaries where one dictionary contains the keys that meet the condition and the other dictionary contains keys that do not meet the condition. This can be useful in scenarios where you would like to separate out dictionary entries based on specific conditions.

Function Definition

The following is the definition of the group_dict_by_key function:

def group_dict_by_key(cond, d):
    """
    Group dictionary keys based on a condition.

    Args:
        cond (function): Condition to split dictionary.
        d (dict): The dictionary to group.

    Returns:
        tuple: Two dictionaries split based on the condition.
    """
    return_val = [{}, {}]
    for key in d.keys():
        match = bool(cond(key))
        ind = int(not match)
        return_val[ind][key] = d[key]
    return (*return_val,)

Arguments:

The group_dict_by_key function accepts the following two arguments:

Argument	Type	Description
cond	function	A function that defines the condition based on which the dictionary keys will be split. This function should take a key as input and return a Boolean value indicating whether the key meets the condition or not.
d	dict	The dictionary that will be split into two dictionaries based on the condition provided by the cond function.

Returns:

The group_dict_by_key function returns two dictionaries:

1. The first dictionary contains keys that satisfy the condition specified by the cond function.

2. The second dictionary contains keys that do not satisfy the cond function.

The returned dictionaries have the same values mapped to the same keys as the original dictionary.

Usage Example:

Example 1:

Consider having a dictionary of student marks and the goal is to group the students into those who have scored 60 and above (pass) and below 60 (fail). The cond function will check if the marks are greater than or equal to 60.

students_marks = {
    "John": 85,
    "Peter": 60,
    "Tracy": 72,
    "Paul": 50,
    "Angela": 67,
    "Robert": 40,
}

# define the condition function to check if marks >= 60
cond = lambda marks: marks >= 60

pass_students, fail_students = group_dict_by_key(cond, students_marks)

The two dictionaries returned from group_dict_by_key would be:

pass_students = {
    "John": 85,
    "Peter": 60,
    "Tracy": 72,
    "Angela": 67,
}

fail_students = {"Paul": 50, "Robert": 40}

Example 2:

If you have a dictionary of items and their prices, and you want to separate them into items that are below or equal to $20 and items that cost more than $20:

items_prices = {
    "apple": 2,
    "orange": 3,
    "mango": 1,
    "blueberry": 5,
    "grape": 10,
    "guava": 25,
    "dragon fruit": 50,
}

# define the condition function to check if price > 20
cond = lambda price: price > 20

pricey, affordable = group_dict_by_key(cond, items_prices)

The returned dictionaries would be:

pricey = {
    "guava": 25,
    "dragon fruit": 50,
}

affordable = {
    "apple": 2,
    "orange": 3,
    "mango": 1,
    "blueberry": 5,
    "grape": 10,
}