[ADD] : maths joint probabilty distribution

maths/joint_probability_distribution.py

@@ -0,0 +1,44 @@
+# https://en.wikipedia.org/wiki/Joint_probability_distribution
+# Function to calculate the joint probability distribution
+def calculate_joint_probability(
+    x_values: list, y_values: list, x_probabilities: list, y_probabilities: list
+) -> dict:
+    """
+    Given two random variables that are defined on the same probability space,
+    [1] the joint probability distribution is the corresponding probability distribution on all possible pairs of outputs.
+    The joint distribution can just as well be considered for any given number of random variables.
+
+    Args:
+        lst (List[int]): The X values.
+        2nd (List[int]): The y values.
+        3rd (List[int]): The x probability.
+        4th (List[int]): The y probability.
+
+    Returns:
+        List[int]: The Joint probability.
+
+    Examples:
+    >>> calculate_joint_probability([1],[1],[1],[1])
+    {(1,1):1}
+    >>> calculate_joint_probability([1][1,2][0.5][0.1,0.5])
+    {(1,1):0.05 , (1,2):0.25}
+
+    """
+    joint_distribution = {}
+
+    # Calculate the joint probability for all combinations of (X, Y)
+    for x, x_prob in zip(x_values, x_probabilities):
+        for y, y_prob in zip(y_values, y_probabilities):
+            joint_prob = x_prob * y_prob
+            joint_distribution[(x, y)] = joint_prob
+    return joint_distribution
+
+
+def main() -> None:
+    print(calculate_joint_probability([1],[1,2],[0.5],[0.1,0,5]))
+
+if __name__ == "__main__":
+    import doctest
+
+    ans = main()
+    doctest.testmod()