Added mean absolute error in linear regression (#7003)

* Added mean absolute error in linear regression

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Co-authored-by: Caeden Perelli-Harris <caedenperelliharris@gmail.com>

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* Update linear_regression.py

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
Co-authored-by: Caeden Perelli-Harris <caedenperelliharris@gmail.com>

machine_learning/linear_regression.py

@@ -17,9 +17,8 @@ def collect_dataset():
     :return : dataset obtained from the link, as matrix
     """
     response = requests.get(
-        "https://raw.githubusercontent.com/yashLadha/"
-        + "The_Math_of_Intelligence/master/Week1/ADRvs"
-        + "Rating.csv"
+        "https://raw.githubusercontent.com/yashLadha/The_Math_of_Intelligence/"
+        "master/Week1/ADRvsRating.csv"
     )
     lines = response.text.splitlines()
     data = []
@@ -87,6 +86,16 @@ def run_linear_regression(data_x, data_y):
     return theta
 
 
+def mean_absolute_error(predicted_y, original_y):
+    """Return sum of square error for error calculation
+    :param predicted_y   : contains the output of prediction (result vector)
+    :param original_y    : contains values of expected outcome
+    :return          : mean absolute error computed from given feature's
+    """
+    total = sum(abs(y - predicted_y[i]) for i, y in enumerate(original_y))
+    return total / len(original_y)
+
+
 def main():
     """Driver function"""
     data = collect_dataset()