Revert accesing columns by name

slope-evaluator/app/trend_slope_computer.py

@@ -9,9 +9,9 @@ def compute(data, warmup_sec):
 
     print(regress)
 
-    X = regress.iloc[:, 'timestamp'].values.reshape(-1, 1)  # values converts it into a numpy array
+    X = regress.iloc[:, 2].values.reshape(-1, 1)  # values converts it into a numpy array
     print(X)
-    Y = regress.iloc[:, 'value'].values.reshape(-1, 1)  # -1 means that calculate the dimension of rows, but have 1 column
+    Y = regress.iloc[:, 3].values.reshape(-1, 1)  # -1 means that calculate the dimension of rows, but have 1 column
     print(Y)
     linear_regressor = LinearRegression()  # create object for the class
     linear_regressor.fit(X, Y)  # perform linear regression