From dff6672fb3c7eda03cb1de39a14b58a1c1d10089 Mon Sep 17 00:00:00 2001
From: Madhav2310 <madhav.mittal.mat19@itbhu.ac.in>
Date: Sun, 21 Aug 2022 05:04:48 +0530
Subject: [PATCH 1/2] Linear Regression function implemented

---
 src/runtime/statistics.py | 78 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/src/runtime/statistics.py b/src/runtime/statistics.py
index 961c731404..f9a5808ae4 100644
--- a/src/runtime/statistics.py
+++ b/src/runtime/statistics.py
@@ -322,3 +322,81 @@ def pstdev(x: list[i32]) -> f64:
     """
     return pvariance(x)**0.5
 
+
+@overload
+def linear_regression(x: list[i32], y: list[i32]) -> tuple[f64, f64]:
+
+    """
+    Returns the slope and intercept of simple linear regression
+    parameters estimated using ordinary least squares.
+
+    """
+    n: i32 = len(x)
+    if len(y) !=  n:
+        raise Exception('linear regression requires that both inputs have same number of data points')
+    if n < 2:
+        raise Exception('linear regression requires at least two data points')
+    xmean: f64 = mean(x)
+    ymean: f64 = mean(y)
+
+    sxy: f64 = 0.0
+    i: i32
+    for i in range(n):
+        sxy += (x[i] - xmean) * (y[i] - ymean)
+
+    sxx: f64 = 0.0
+    j: i32
+    for j in range(n):
+        sxx += (x[j] - xmean) ** 2
+
+    slope: f64
+
+    if sxx == 0:
+        raise Exception('x is constant')
+    else:
+        slope = sxy / sxx
+
+    intercept: f64  = ymean - slope * xmean
+
+    LinReg: tuple[f64, f64] = (slope, intercept)
+
+    return LinReg
+
+@overload
+def linear_regression(x: list[f64], y: list[f64]) -> tuple[f64, f64]:
+
+    """
+    Returns the slope and intercept of simple linear regression
+    parameters estimated using ordinary least squares.
+
+    """
+    n: i32 = len(x)
+    if len(y) !=  n:
+        raise Exception('linear regression requires that both inputs have same number of data points')
+    if n < 2:
+        raise Exception('linear regression requires at least two data points')
+    xmean: f64 = mean(x)
+    ymean: f64 = mean(y)
+
+    sxy: f64 = 0.0
+    i: i32
+    for i in range(n):
+        sxy += (x[i] - xmean) * (y[i] - ymean)
+
+    sxx: f64 = 0.0
+    j: i32
+    for j in range(n):
+        sxx += (x[j] - xmean) ** 2
+
+    slope: f64
+
+    if sxx == 0:
+        raise Exception('x is constant')
+    else:
+        slope = sxy / sxx
+
+    intercept: f64  = ymean - slope * xmean
+
+    LinReg: tuple[f64, f64] = (slope, intercept)
+
+    return LinReg

From c16f9492db4c5b689133bb7e074276f899c81468 Mon Sep 17 00:00:00 2001
From: Smit-create <smitlunagariya.mat18@itbhu.ac.in>
Date: Mon, 29 Aug 2022 16:32:32 +0530
Subject: [PATCH 2/2] Add tests

Co-Authored-By: Madhav <madhav.mittal.mat19@itbhu.ac.in>
---
 integration_tests/test_statistics.py | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/integration_tests/test_statistics.py b/integration_tests/test_statistics.py
index 4228072418..25f15893fb 100644
--- a/integration_tests/test_statistics.py
+++ b/integration_tests/test_statistics.py
@@ -1,4 +1,5 @@
-from statistics import (mean, fmean, geometric_mean, harmonic_mean, variance, stdev, pvariance, pstdev)
+from statistics import (mean, fmean, geometric_mean, harmonic_mean, variance,
+                        stdev, pvariance, pstdev, linear_regression)
 from ltypes import i32, f64, i64, f32
 
 eps: f64
@@ -122,6 +123,30 @@ def test_pstdev():
     k = pstdev(b)
     assert abs(k - 0.37537181567080935) < eps
 
+def test_linear_regression():
+    c: list[f64]
+    c = [2.74, 1.23, 2.63, 2.22, 3.0, 1.98]
+    d: list[f64]
+    d = [9.4, 1.23, 2.63, 22.4, 1.9, 13.98]
+
+    slope: f64
+    intercept: f64
+    slope, intercept = linear_regression(c, d)
+
+    assert abs(slope + 0.6098133124816717) < eps
+    assert abs(intercept - 9.992570618707845) < eps
+
+    a: list[i32]
+    b: list[i32]
+    a = [12, 24, 2, 1, 43, 53, 23]
+    b = [2, 13, 14, 63, 49, 7, 3]
+
+    slope, intercept = linear_regression(a, b)
+
+    assert abs(slope + 0.18514007308160782) < eps
+    assert abs(intercept - 25.750304506699152) < eps
+
+
 def check():
     test_mean()
     test_geometric_mean()
@@ -131,5 +156,6 @@ def check():
     test_stdev()
     test_pvariance()
     test_pstdev()
+    test_linear_regression()
 
 check()