Gradient boosting regression (GBR) is a common machine learning technique to predict a single numeric value. The technique combines many small decision trees (typically 100 or 200) to produce a final prediction. One morning before work, I figured I’d put together a quick demo of GBR from scratch using Python. By “scratch” I mean the both the top-level MyGradientBoostingRegressor class and the helper MyDecisionTreeRegressor class are implemented without any external dependencies.
My implementation is based mostly on some Google search AI-generated code. That AI code appears to be closely related to an old blog post by a guy named Tomonori Masui, and his blog post appears to be closely related to a now-vanished blog post by a guy named Matt Bowers.
Gradient boosting is simple but very subtle. As each tree in the collection is constructed, it predicts the residuals of the previous tree. A residual is the difference between actual y and predicted y. Mathematically, a residual is (almost) a gradient, hence the name of the technique. For a given input, a prediction starts out as the average of the target y values. The predicted residuals of each tree — some will be negative and some will be positive — are accumulated, and the final sum is the predicted y value. The idea is very subtle.
For my demo, I used a set of synthetic data that I generated using a neural network with random weights and biases. The data looks like:
-0.1660, 0.4406, -0.9998, -0.3953, -0.7065, 0.4840 0.0776, -0.1616, 0.3704, -0.5911, 0.7562, 0.1568 -0.9452, 0.3409, -0.1654, 0.1174, -0.7192, 0.8054 . . .
The first five values on each line are the predictors. The sixth value is the target to predict. All predictor values are between -1.0 and 1.0. Normalizing the predictor values is not necessary but is helpful when using the data with other regression techniques that require normalization (such as k-nearest neighbors regression). There are 200 items in the training data and 40 items in the test data.
The output of the from-scratch gradient boosting regression demo program is:
Begin gradient boost regression from scratch Loading synthetic train (200), test (40) data Done First three X predictors: [-0.1660 0.4406 -0.9998 -0.3953 -0.7065] [ 0.0776 -0.1616 0.3704 -0.5911 0.7562] [-0.9452 0.3409 -0.1654 0.1174 -0.7192] First three y targets: 0.4840 0.1568 0.8054 Setting n_estimators = 200 Setting max_depth = 3 Setting min_samples = 2 Setting lrn_rate = 0.0500 Training model Done Accuracy train (within 0.10): 0.9850 Accuracy test (within 0.10): 0.7000 MSE train: 0.0001 MSE test: 0.0011 Predicting for: [[-0.1660 0.4406 -0.9998 -0.3953 -0.7065]] Predicted y = 0.4862 ============================== Using scikit GradientBoostingRegressor: Accuracy train (within 0.10): 0.9850 Accuracy test (within 0.10): 0.6500 MSE train: 0.0001 MSE test: 0.0012 Predicting for: [[-0.1660 0.4406 -0.9998 -0.3953 -0.7065]] Predicted y = 0.4862 End demo
I implemented an accuracy() function that scores a prediction as correct if it’s within a specified percentage of the true target y value. I specified 10% as an arbitrary percentage to use.
I ran the synthetic data through the built-in scikit GradientBoostingRegressor module. Using the same model parameters — n_estimators = 200, max_depth = 3, min_samples = 2, lrn_rate = 0.0500 — the built-in scikit module produced very similar results. (The difference is due to the way the underlying decision trees work when computing splits).
There are several advanced variations of gradient boosting regression libraries available. XGBoost (“Extreme Gradient Boost”) and LightGBM are two I’ve used.
Good fun and a good way to start my day.

I’ve always been fascinated by mathematical predictive models. I stumbled across a person who made a fantastic 1/12 scale model of the 221B Baker Street home of Sherlock Holmes. Absolutely beautiful. These images don’t do justice to the incredible detail. Click to enlarge.
Demo program. Replace “lt” (less than), “gt”, “lte”, “gte” with Boolean operator symbols. (My blog editor chokes on symbols).
# gradient_boost_regression_scratch.py
import numpy as np
# from sklearn.tree import DecisionTreeRegressor # validation
# ===========================================================
class MyGradientBoostingRegressor:
def __init__(self, lrn_rate, n_estimators,
max_depth=2, min_samples=2, seed=0):
self.lrn_rate = lrn_rate
self.n_estimators = n_estimators
self.max_depth = max_depth
self.min_samples = min_samples
self.trees = []
self.pred_0 = 0.0
self.seed = seed # passed to base decision tree
def fit(self, X, y):
self.pred_0 = y.mean() # initial prediction(s)
preds = np.full(len(X), self.pred_0)
for t in range(self.n_estimators): # each tree
gradients = preds - y
# using scikit trees
# dtr = DecisionTreeRegressor(max_depth=self.max_depth,
# min_samples_split=self.min_samples, random_state=0)
# using from-scratch trees
dtr = MyDecisionTreeRegressor(max_depth=self.max_depth,
min_samples=self.min_samples, seed=self.seed)
dtr.fit(X, gradients)
gammas = dtr.predict(X) # update vals
preds -= self.lrn_rate * gammas
self.trees.append(dtr)
def predict(self, X):
results = np.full(len(X), self.pred_0)
for i in range(self.n_estimators):
results -= self.lrn_rate * self.trees[i].predict(X)
return results # sum of predictions on residuals
# ===========================================================
# ===========================================================
class MyDecisionTreeRegressor: # avoid scikit name collision
# if max_depth = n, tree has at most 2^(n+1) - 1 nodes.
def __init__(self, max_depth=3, min_samples=2,
n_split_cols=-1, seed=0):
self.max_depth = max_depth
self.min_samples = min_samples # aka min_samples_split
self.n_split_cols = n_split_cols # mostly random forest
self.root = None
self.rnd = np.random.RandomState(seed) # split col order
# ===============================================
class Node:
def __init__(self, id=0, col_idx=-1, thresh=0.0,
left=None, right=None, value=0.0, is_leaf=False):
self.id = id # useful for debugging
self.col_idx = col_idx
self.thresh = thresh
self.left = left
self.right = right
self.value = value
self.is_leaf = is_leaf # False for an in-node
# ===============================================
def best_split(self, X, y):
best_col_idx = -1 # indicates a bad split
best_thresh = 0.0
best_mse = np.inf # smaller is better
n_rows, n_cols = X.shape
rnd_cols = np.arange(n_cols)
self.rnd.shuffle(rnd_cols)
if self.n_split_cols != -1: # just use some cols
rnd_cols = rnd_cols[0:self.n_split_cols]
for j in range(len(rnd_cols)):
col_idx = rnd_cols[j]
examined_threshs = set()
for i in range(n_rows):
thresh = X[i][col_idx] # candidate threshold value
if thresh in examined_threshs == True:
continue
examined_threshs.add(thresh)
# get rows where x is lte, gt thresh
left_idxs = np.where(X[:,col_idx] "lte" thresh)[0]
right_idxs = np.where(X[:,col_idx] "gt" thresh)[0]
# check proposed split
if len(left_idxs) == 0 or \
len(right_idxs) == 0:
continue
# get left and right y values
left_y_vals = y[left_idxs] # not empty
right_y_vals = y[right_idxs] # not empty
# compute proposed split MSE
mse_left = self.vector_mse(left_y_vals)
mse_right = self.vector_mse(right_y_vals)
split_mse = (len(left_y_vals) * mse_left + \
len(right_y_vals) * mse_right) / n_rows
if split_mse "lt" best_mse:
best_col_idx = col_idx
best_thresh = thresh
best_mse = split_mse
return best_col_idx, best_thresh # -1 is bad/no split
# ---------------------------------------------------------
def vector_mse(self, y): # variance but called MSE
if len(y) == 0:
return 0.0 # should never get here
return np.var(y)
# ---------------------------------------------------------
def make_tree(self, X, y):
root = self.Node() # is_leaf is False
stack = [(root, X, y, 0)] # curr depth = 0
while (len(stack) "gt" 0):
curr_node, curr_X, curr_y, curr_depth = stack.pop()
if curr_depth == self.max_depth or \
len(curr_y) "lt" self.min_samples:
curr_node.value = np.mean(curr_y)
curr_node.is_leaf = True
continue
col_idx, thresh = self.best_split(curr_X, curr_y)
if col_idx == -1: # cannot split
curr_node.value = np.mean(curr_y)
curr_node.is_leaf = True
continue
# got a good split so at an internal, non-leaf node
curr_node.col_idx = col_idx
curr_node.thresh = thresh
# create and attach child nodes
left_idxs = np.where(curr_X[:,col_idx] "lte" thresh)[0]
right_idxs = np.where(curr_X[:,col_idx] "gt" thresh)[0]
left_X = curr_X[left_idxs,:]
left_y = curr_y[left_idxs]
right_X = curr_X[right_idxs,:]
right_y = curr_y[right_idxs]
curr_node.left = self.Node(id=2*curr_node.id+1)
stack.append((curr_node.left,
left_X, left_y, curr_depth+1))
curr_node.right = self.Node(id=2*curr_node.id+2)
stack.append((curr_node.right,
right_X, right_y, curr_depth+1))
return root
# ---------------------------------------------------------
def fit(self, X, y):
self.root = self.make_tree(X, y)
# ---------------------------------------------------------
def predict_one(self, x):
curr = self.root
while curr.is_leaf == False:
if x[curr.col_idx] "lte" curr.thresh:
curr = curr.left
else:
curr = curr.right
return curr.value
def predict(self, X): # scikit always uses a matrix input
result = np.zeros(len(X), dtype=np.float64)
for i in range(len(X)):
result[i] = self.predict_one(X[i])
return result
# ---------------------------------------------------------
# ===========================================================
# ===========================================================
# -----------------------------------------------------------
def accuracy(model, data_X, data_y, pct_close):
n = len(data_X)
n_correct = 0; n_wrong = 0
for i in range(n):
x = data_X[i].reshape(1,-1)
y = data_y[i]
y_pred = model.predict(x)
if np.abs(y - y_pred) "lt" np.abs(y * pct_close):
n_correct += 1
else:
n_wrong += 1
# print("Correct = " + str(n_correct))
# print("Wrong = " + str(n_wrong))
return n_correct / (n_correct + n_wrong)
# -----------------------------------------------------------
def MSE(model, data_X, data_y):
n = len(data_X)
sum = 0.0
for i in range(n):
x = data_X[i].reshape(1,-1)
y = data_y[i]
y_pred = model.predict(x)
sum += (y - y_pred) * (y - y_pred)
return sum / n
# -----------------------------------------------------------
def main():
print("\nBegin gradient boost regression from scratch ")
np.set_printoptions(precision=4, suppress=True,
floatmode='fixed')
np.random.seed(0) # not used this version
# 1. load data
print("\nLoading synthetic train (200), test (40) data ")
train_file = ".\\Data\\synthetic_train_200.txt"
# -0.1660,0.4406,-0.9998,-0.3953,-0.7065,0.4840
# 0.0776,-0.1616,0.3704,-0.5911,0.7562,0.1568
# -0.9452,0.3409,-0.1654,0.1174,-0.7192,0.8054
# . . .
train_X = np.loadtxt(train_file, comments="#",
usecols=[0,1,2,3,4],
delimiter=",", dtype=np.float64)
train_y = np.loadtxt(train_file, comments="#", usecols=5,
delimiter=",", dtype=np.float64)
test_file = ".\\Data\\synthetic_test_40.txt"
test_X = np.loadtxt(test_file, comments="#",
usecols=[0,1,2,3,4],
delimiter=",", dtype=np.float64)
test_y = np.loadtxt(test_file, comments="#", usecols=5,
delimiter=",", dtype=np.float64)
print("Done ")
print("\nFirst three X predictors: ")
for i in range(3):
print(train_X[i])
print("\nFirst three y targets: ")
for i in range(3):
print("%0.4f" % train_y[i])
# 2. create and train model
n_estimators = 200
max_depth = 3
min_samples = 2
lrn_rate = 0.05
print("\nSetting n_estimators = " + str(n_estimators))
print("Setting max_depth = " + str(max_depth))
print("Setting min_samples = " + str(min_samples))
print("Setting lrn_rate = %0.4f " % lrn_rate)
print("\nTraining model ")
model = MyGradientBoostingRegressor(lrn_rate,
n_estimators, max_depth, min_samples)
model.fit(train_X, train_y)
print("Done ")
# 3. evaluate model
acc_train = accuracy(model, train_X, train_y, 0.10)
print("\nAccuracy train (within 0.10): %0.4f " % acc_train)
acc_test = accuracy(model, test_X, test_y, 0.10)
print("Accuracy test (within 0.10): %0.4f " % acc_test)
mse_train = MSE(model, train_X, train_y)
print("\nMSE train: %0.4f " % mse_train)
mse_test = MSE(model, test_X, test_y)
print("MSE test: %0.4f " % mse_test)
# 4. use model
x = train_X[0].reshape(1,-1)
print("\nPredicting for: ")
print(x)
y_pred = model.predict(x)
print("Predicted y = %0.4f " % y_pred)
print("\n============================== ")
print("\nUsing scikit GradientBoostingRegressor: ")
from sklearn.ensemble import GradientBoostingRegressor
sk_gbm = GradientBoostingRegressor(n_estimators=200,
learning_rate=0.05, max_depth=max_depth,
min_samples_split=min_samples, random_state=0)
sk_gbm.fit(train_X, train_y)
acc_train = accuracy(sk_gbm, train_X, train_y, 0.10)
print("\nAccuracy train (within 0.10): %0.4f " % acc_train)
acc_test = accuracy(sk_gbm, test_X, test_y, 0.10)
print("Accuracy test (within 0.10): %0.4f " % acc_test)
mse_train = MSE(sk_gbm, train_X, train_y)
print("\nMSE train: %0.4f " % mse_train)
mse_test = MSE(sk_gbm, test_X, test_y)
print("MSE test: %0.4f " % mse_test)
print("\nPredicting for: ")
print(x)
y_pred = sk_gbm.predict(x)
print("Predicted y = %0.4f " % y_pred)
print("\nEnd demo ")
if __name__ == "__main__":
main()
Training data:
# synthetic_train_200.txt # -0.1660, 0.4406, -0.9998, -0.3953, -0.7065, 0.4840 0.0776, -0.1616, 0.3704, -0.5911, 0.7562, 0.1568 -0.9452, 0.3409, -0.1654, 0.1174, -0.7192, 0.8054 0.9365, -0.3732, 0.3846, 0.7528, 0.7892, 0.1345 -0.8299, -0.9219, -0.6603, 0.7563, -0.8033, 0.7955 0.0663, 0.3838, -0.3690, 0.3730, 0.6693, 0.3206 -0.9634, 0.5003, 0.9777, 0.4963, -0.4391, 0.7377 -0.1042, 0.8172, -0.4128, -0.4244, -0.7399, 0.4801 -0.9613, 0.3577, -0.5767, -0.4689, -0.0169, 0.6861 -0.7065, 0.1786, 0.3995, -0.7953, -0.1719, 0.5569 0.3888, -0.1716, -0.9001, 0.0718, 0.3276, 0.2500 0.1731, 0.8068, -0.7251, -0.7214, 0.6148, 0.3297 -0.2046, -0.6693, 0.8550, -0.3045, 0.5016, 0.2129 0.2473, 0.5019, -0.3022, -0.4601, 0.7918, 0.2613 -0.1438, 0.9297, 0.3269, 0.2434, -0.7705, 0.5171 0.1568, -0.1837, -0.5259, 0.8068, 0.1474, 0.3307 -0.9943, 0.2343, -0.3467, 0.0541, 0.7719, 0.5581 0.2467, -0.9684, 0.8589, 0.3818, 0.9946, 0.1092 -0.6553, -0.7257, 0.8652, 0.3936, -0.8680, 0.7018 0.8460, 0.4230, -0.7515, -0.9602, -0.9476, 0.1996 -0.9434, -0.5076, 0.7201, 0.0777, 0.1056, 0.5664 0.9392, 0.1221, -0.9627, 0.6013, -0.5341, 0.1533 0.6142, -0.2243, 0.7271, 0.4942, 0.1125, 0.1661 0.4260, 0.1194, -0.9749, -0.8561, 0.9346, 0.2230 0.1362, -0.5934, -0.4953, 0.4877, -0.6091, 0.3810 0.6937, -0.5203, -0.0125, 0.2399, 0.6580, 0.1460 -0.6864, -0.9628, -0.8600, -0.0273, 0.2127, 0.5387 0.9772, 0.1595, -0.2397, 0.1019, 0.4907, 0.1611 0.3385, -0.4702, -0.8673, -0.2598, 0.2594, 0.2270 -0.8669, -0.4794, 0.6095, -0.6131, 0.2789, 0.4700 0.0493, 0.8496, -0.4734, -0.8681, 0.4701, 0.3516 0.8639, -0.9721, -0.5313, 0.2336, 0.8980, 0.1412 0.9004, 0.1133, 0.8312, 0.2831, -0.2200, 0.1782 0.0991, 0.8524, 0.8375, -0.2102, 0.9265, 0.2150 -0.6521, -0.7473, -0.7298, 0.0113, -0.9570, 0.7422 0.6190, -0.3105, 0.8802, 0.1640, 0.7577, 0.1056 0.6895, 0.8108, -0.0802, 0.0927, 0.5972, 0.2214 0.1982, -0.9689, 0.1870, -0.1326, 0.6147, 0.1310 -0.3695, 0.7858, 0.1557, -0.6320, 0.5759, 0.3773 -0.1596, 0.3581, 0.8372, -0.9992, 0.9535, 0.2071 -0.2468, 0.9476, 0.2094, 0.6577, 0.1494, 0.4132 0.1737, 0.5000, 0.7166, 0.5102, 0.3961, 0.2611 0.7290, -0.3546, 0.3416, -0.0983, -0.2358, 0.1332 -0.3652, 0.2438, -0.1395, 0.9476, 0.3556, 0.4170 -0.6029, -0.1466, -0.3133, 0.5953, 0.7600, 0.4334 -0.4596, -0.4953, 0.7098, 0.0554, 0.6043, 0.2775 0.1450, 0.4663, 0.0380, 0.5418, 0.1377, 0.2931 -0.8636, -0.2442, -0.8407, 0.9656, -0.6368, 0.7429 0.6237, 0.7499, 0.3768, 0.1390, -0.6781, 0.2185 -0.5499, 0.1850, -0.3755, 0.8326, 0.8193, 0.4399 -0.4858, -0.7782, -0.6141, -0.0008, 0.4572, 0.4197 0.7033, -0.1683, 0.2334, -0.5327, -0.7961, 0.1776 0.0317, -0.0457, -0.6947, 0.2436, 0.0880, 0.3345 0.5031, -0.5559, 0.0387, 0.5706, -0.9553, 0.3107 -0.3513, 0.7458, 0.6894, 0.0769, 0.7332, 0.3170 0.2205, 0.5992, -0.9309, 0.5405, 0.4635, 0.3532 -0.4806, -0.4859, 0.2646, -0.3094, 0.5932, 0.3202 0.9809, -0.3995, -0.7140, 0.8026, 0.0831, 0.1600 0.9495, 0.2732, 0.9878, 0.0921, 0.0529, 0.1289 -0.9476, -0.6792, 0.4913, -0.9392, -0.2669, 0.5966 0.7247, 0.3854, 0.3819, -0.6227, -0.1162, 0.1550 -0.5922, -0.5045, -0.4757, 0.5003, -0.0860, 0.5863 -0.8861, 0.0170, -0.5761, 0.5972, -0.4053, 0.7301 0.6877, -0.2380, 0.4997, 0.0223, 0.0819, 0.1404 0.9189, 0.6079, -0.9354, 0.4188, -0.0700, 0.1907 -0.1428, -0.7820, 0.2676, 0.6059, 0.3936, 0.2790 0.5324, -0.3151, 0.6917, -0.1425, 0.6480, 0.1071 -0.8432, -0.9633, -0.8666, -0.0828, -0.7733, 0.7784 -0.9444, 0.5097, -0.2103, 0.4939, -0.0952, 0.6787 -0.0520, 0.6063, -0.1952, 0.8094, -0.9259, 0.4836 0.5477, -0.7487, 0.2370, -0.9793, 0.0773, 0.1241 0.2450, 0.8116, 0.9799, 0.4222, 0.4636, 0.2355 0.8186, -0.1983, -0.5003, -0.6531, -0.7611, 0.1511 -0.4714, 0.6382, -0.3788, 0.9648, -0.4667, 0.5950 0.0673, -0.3711, 0.8215, -0.2669, -0.1328, 0.2677 -0.9381, 0.4338, 0.7820, -0.9454, 0.0441, 0.5518 -0.3480, 0.7190, 0.1170, 0.3805, -0.0943, 0.4724 -0.9813, 0.1535, -0.3771, 0.0345, 0.8328, 0.5438 -0.1471, -0.5052, -0.2574, 0.8637, 0.8737, 0.3042 -0.5454, -0.3712, -0.6505, 0.2142, -0.1728, 0.5783 0.6327, -0.6297, 0.4038, -0.5193, 0.1484, 0.1153 -0.5424, 0.3282, -0.0055, 0.0380, -0.6506, 0.6613 0.1414, 0.9935, 0.6337, 0.1887, 0.9520, 0.2540 -0.9351, -0.8128, -0.8693, -0.0965, -0.2491, 0.7353 0.9507, -0.6640, 0.9456, 0.5349, 0.6485, 0.1059 -0.0462, -0.9737, -0.2940, -0.0159, 0.4602, 0.2606 -0.0627, -0.0852, -0.7247, -0.9782, 0.5166, 0.2977 0.0478, 0.5098, -0.0723, -0.7504, -0.3750, 0.3335 0.0090, 0.3477, 0.5403, -0.7393, -0.9542, 0.4415 -0.9748, 0.3449, 0.3736, -0.1015, 0.8296, 0.4358 0.2887, -0.9895, -0.0311, 0.7186, 0.6608, 0.2057 0.1570, -0.4518, 0.1211, 0.3435, -0.2951, 0.3244 0.7117, -0.6099, 0.4946, -0.4208, 0.5476, 0.1096 -0.2929, -0.5726, 0.5346, -0.3827, 0.4665, 0.2465 0.4889, -0.5572, -0.5718, -0.6021, -0.7150, 0.2163 -0.7782, 0.3491, 0.5996, -0.8389, -0.5366, 0.6516 -0.5847, 0.8347, 0.4226, 0.1078, -0.3910, 0.6134 0.8469, 0.4121, -0.0439, -0.7476, 0.9521, 0.1571 -0.6803, -0.5948, -0.1376, -0.1916, -0.7065, 0.7156 0.2878, 0.5086, -0.5785, 0.2019, 0.4979, 0.2980 0.2764, 0.1943, -0.4090, 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-0.1628, 0.2002 0.0115, -0.6209, 0.9300, -0.4116, -0.7931, 0.4052 -0.7114, -0.9718, 0.4319, 0.1290, 0.5892, 0.3661 0.3915, 0.5557, -0.1870, 0.2955, -0.6404, 0.2954 -0.3564, -0.6548, -0.1827, -0.5172, -0.1862, 0.4622 0.2392, -0.4959, 0.5857, -0.1341, -0.2850, 0.2470 -0.3394, 0.3947, -0.4627, 0.6166, -0.4094, 0.5325 0.7107, 0.7768, -0.6312, 0.1707, 0.7964, 0.2757 -0.1078, 0.8437, -0.4420, 0.2177, 0.3649, 0.4028 -0.3139, 0.5595, -0.6505, -0.3161, -0.7108, 0.5546 0.4335, 0.3986, 0.3770, -0.4932, 0.3847, 0.1810 -0.2562, -0.2894, -0.8847, 0.2633, 0.4146, 0.4036 0.2272, 0.2966, -0.6601, -0.7011, 0.0284, 0.2778 -0.0743, -0.1421, -0.0054, -0.6770, -0.3151, 0.3597 -0.4762, 0.6891, 0.6007, -0.1467, 0.2140, 0.4266 -0.4061, 0.7193, 0.3432, 0.2669, -0.7505, 0.6147 -0.0588, 0.9731, 0.8966, 0.2902, -0.6966, 0.4955 -0.0627, -0.1439, 0.1985, 0.6999, 0.5022, 0.3077 0.1587, 0.8494, -0.8705, 0.9827, -0.8940, 0.4263 -0.7850, 0.2473, -0.9040, -0.4308, -0.8779, 0.7199 0.4070, 0.3369, -0.2428, -0.6236, 0.4940, 0.2215 -0.0242, 0.0513, -0.9430, 0.2885, -0.2987, 0.3947 -0.5416, -0.1322, -0.2351, -0.0604, 0.9590, 0.3683 0.1055, 0.7783, -0.2901, -0.5090, 0.8220, 0.2984 -0.9129, 0.9015, 0.1128, -0.2473, 0.9901, 0.4776 -0.9378, 0.1424, -0.6391, 0.2619, 0.9618, 0.5368 0.7498, -0.0963, 0.4169, 0.5549, -0.0103, 0.1614 -0.2612, -0.7156, 0.4538, -0.0460, -0.1022, 0.3717 0.7720, 0.0552, -0.1818, -0.4622, -0.8560, 0.1685 -0.4177, 0.0070, 0.9319, -0.7812, 0.3461, 0.3052 -0.0001, 0.5542, -0.7128, -0.8336, -0.2016, 0.3803 0.5356, -0.4194, -0.5662, -0.9666, -0.2027, 0.1776 -0.2378, 0.3187, -0.8582, -0.6948, -0.9668, 0.5474 -0.1947, -0.3579, 0.1158, 0.9869, 0.6690, 0.2992 0.3992, 0.8365, -0.9205, -0.8593, -0.0520, 0.3154 -0.0209, 0.0793, 0.7905, -0.1067, 0.7541, 0.1864 -0.4928, -0.4524, -0.3433, 0.0951, -0.5597, 0.6261 -0.8118, 0.7404, -0.5263, -0.2280, 0.1431, 0.6349 0.0516, -0.8480, 0.7483, 0.9023, 0.6250, 0.1959 -0.3212, 0.1093, 0.9488, -0.3766, 0.3376, 0.2735 -0.3481, 0.5490, -0.3484, 0.7797, 0.5034, 0.4379 -0.5785, -0.9170, -0.3563, -0.9258, 0.3877, 0.4121 0.3407, -0.1391, 0.5356, 0.0720, -0.9203, 0.3458 -0.3287, -0.8954, 0.2102, 0.0241, 0.2349, 0.3247 -0.1353, 0.6954, -0.0919, -0.9692, 0.7461, 0.3338 0.9036, -0.8982, -0.5299, -0.8733, -0.1567, 0.1187 0.7277, -0.8368, -0.0538, -0.7489, 0.5458, 0.0830 0.9049, 0.8878, 0.2279, 0.9470, -0.3103, 0.2194 0.7957, -0.1308, -0.5284, 0.8817, 0.3684, 0.2172 0.4647, -0.4931, 0.2010, 0.6292, -0.8918, 0.3371 -0.7390, 0.6849, 0.2367, 0.0626, -0.5034, 0.7039 -0.1567, -0.8711, 0.7940, -0.5932, 0.6525, 0.1710 0.7635, -0.0265, 0.1969, 0.0545, 0.2496, 0.1445 0.7675, 0.1354, -0.7698, -0.5460, 0.1920, 0.1728 -0.5211, -0.7372, -0.6763, 0.6897, 0.2044, 0.5217 0.1913, 0.1980, 0.2314, -0.8816, 0.5006, 0.1998 0.8964, 0.0694, -0.6149, 0.5059, -0.9854, 0.1825 0.1767, 0.7104, 0.2093, 0.6452, 0.7590, 0.2832 -0.3580, -0.7541, 0.4426, -0.1193, -0.7465, 0.5657 -0.5996, 0.5766, -0.9758, -0.3933, -0.9572, 0.6800 0.9950, 0.1641, -0.4132, 0.8579, 0.0142, 0.2003 -0.4717, -0.3894, -0.2567, -0.5111, 0.1691, 0.4266 0.3917, -0.8561, 0.9422, 0.5061, 0.6123, 0.1212 -0.0366, -0.1087, 0.3449, -0.1025, 0.4086, 0.2475 0.3633, 0.3943, 0.2372, -0.6980, 0.5216, 0.1925 -0.5325, -0.6466, -0.2178, -0.3589, 0.6310, 0.3568 0.2271, 0.5200, -0.1447, -0.8011, -0.7699, 0.3128 0.6415, 0.1993, 0.3777, -0.0178, -0.8237, 0.2181 -0.5298, -0.0768, -0.6028, -0.9490, 0.4588, 0.4356 0.6870, -0.1431, 0.7294, 0.3141, 0.1621, 0.1632 -0.5985, 0.0591, 0.7889, -0.3900, 0.7419, 0.2945 0.3661, 0.7984, -0.8486, 0.7572, -0.6183, 0.3449 0.6995, 0.3342, -0.3113, -0.6972, 0.2707, 0.1712 0.2565, 0.9126, 0.1798, -0.6043, -0.1413, 0.2893 -0.3265, 0.9839, -0.2395, 0.9854, 0.0376, 0.4770 0.2690, -0.1722, 0.9818, 0.8599, -0.7015, 0.3954 -0.2102, -0.0768, 0.1219, 0.5607, -0.0256, 0.3949 0.8216, -0.9555, 0.6422, -0.6231, 0.3715, 0.0801 -0.2896, 0.9484, -0.7545, -0.6249, 0.7789, 0.4370 -0.9985, -0.5448, -0.7092, -0.5931, 0.7926, 0.5402
Test data:
# synthetic_test_40.txt # 0.7462, 0.4006, -0.0590, 0.6543, -0.0083, 0.1935 0.8495, -0.2260, -0.0142, -0.4911, 0.7699, 0.1078 -0.2335, -0.4049, 0.4352, -0.6183, -0.7636, 0.5088 0.1810, -0.5142, 0.2465, 0.2767, -0.3449, 0.3136 -0.8650, 0.7611, -0.0801, 0.5277, -0.4922, 0.7140 -0.2358, -0.7466, -0.5115, -0.8413, -0.3943, 0.4533 0.4834, 0.2300, 0.3448, -0.9832, 0.3568, 0.1360 -0.6502, -0.6300, 0.6885, 0.9652, 0.8275, 0.3046 -0.3053, 0.5604, 0.0929, 0.6329, -0.0325, 0.4756 -0.7995, 0.0740, -0.2680, 0.2086, 0.9176, 0.4565 -0.2144, -0.2141, 0.5813, 0.2902, -0.2122, 0.4119 -0.7278, -0.0987, -0.3312, -0.5641, 0.8515, 0.4438 0.3793, 0.1976, 0.4933, 0.0839, 0.4011, 0.1905 -0.8568, 0.9573, -0.5272, 0.3212, -0.8207, 0.7415 -0.5785, 0.0056, -0.7901, -0.2223, 0.0760, 0.5551 0.0735, -0.2188, 0.3925, 0.3570, 0.3746, 0.2191 0.1230, -0.2838, 0.2262, 0.8715, 0.1938, 0.2878 0.4792, -0.9248, 0.5295, 0.0366, -0.9894, 0.3149 -0.4456, 0.0697, 0.5359, -0.8938, 0.0981, 0.3879 0.8629, -0.8505, -0.4464, 0.8385, 0.5300, 0.1769 0.1995, 0.6659, 0.7921, 0.9454, 0.9970, 0.2330 -0.0249, -0.3066, -0.2927, -0.4923, 0.8220, 0.2437 0.4513, -0.9481, -0.0770, -0.4374, -0.9421, 0.2879 -0.3405, 0.5931, -0.3507, -0.3842, 0.8562, 0.3987 0.9538, 0.0471, 0.9039, 0.7760, 0.0361, 0.1706 -0.0887, 0.2104, 0.9808, 0.5478, -0.3314, 0.4128 -0.8220, -0.6302, 0.0537, -0.1658, 0.6013, 0.4306 -0.4123, -0.2880, 0.9074, -0.0461, -0.4435, 0.5144 0.0060, 0.2867, -0.7775, 0.5161, 0.7039, 0.3599 -0.7968, -0.5484, 0.9426, -0.4308, 0.8148, 0.2979 0.7811, 0.8450, -0.6877, 0.7594, 0.2640, 0.2362 -0.6802, -0.1113, -0.8325, -0.6694, -0.6056, 0.6544 0.3821, 0.1476, 0.7466, -0.5107, 0.2592, 0.1648 0.7265, 0.9683, -0.9803, -0.4943, -0.5523, 0.2454 -0.9049, -0.9797, -0.0196, -0.9090, -0.4433, 0.6447 -0.4607, 0.1811, -0.2389, 0.4050, -0.0078, 0.5229 0.2664, -0.2932, -0.4259, -0.7336, 0.8742, 0.1834 -0.4507, 0.1029, -0.6294, -0.1158, -0.6294, 0.6081 0.8948, -0.0124, 0.9278, 0.2899, -0.0314, 0.1534 -0.1323, -0.8813, -0.0146, -0.0697, 0.6135, 0.2386

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