add new code for linear regression from scratch in python

Python/linear_regression.py

@@ -0,0 +1,22 @@
+import numpy as np
+
+def lin_reg_pred(x1, x2, y_train, x_test1, x_test2):
+    """
+    linear regression
+    input : training data in list of float
+    output : list of total user prediction in float
+    >>> lin_reg_pred([2,3,4,5], [3,1,2,4],[5,3,4,6], [2,1], [2,2])
+    5.000000000000003
+    """
+    x = []
+    for i in range(len(x1)):
+        x.append([1, x1[i], x2[i]])
+    x = np.array(x)
+    y = np.array(y_train)
+    beta = np.dot(np.dot(np.linalg.inv(np.dot(x.transpose(), x)), x.transpose()), y)
+    prediction = abs(beta[0] + x_test1[0] * beta[1] + x_test2[0] + beta[2])
+    return [prediction]
+
+
+temp = lin_reg_pred([2,3,4,5], [3,1,2,4],[5,3,4,6], [2,1], [2,2])
+print(temp)