r-squared function added

src/matrics_calculator/R_squared.py

@@ -0,0 +1,31 @@
+# r-squared value calcualtion
+def r2(df, predictor, response): 
+    """
+    Calculates r-squared using linear regression.
+
+    Computes the r-squared value (coefficient of determination) using the provided dataframe,
+    predictor column names, and response column name.
+    
+    Parameters
+    ----------
+    df : dataframe
+        Dataframe containing necessary predictor values and response value.
+    predictor : list or string
+        Predictor values to be used in calculating r-sqaured value.
+    response : list or string
+        Response values to be used in calculating r-sqaured value.
+
+    Returns
+    -------
+    float
+        r-sqaured value which is <= 1. 1 is the best score and a score below 0 is worse than 
+        using the mean of the target as predictions.
+
+    Examples
+    --------
+    >>> r2(student_grades, math_test, final_grade)
+    0.88
+    >>> r2(student_grades, [math_test, science_test], absences)
+    -0.32
+    """
+