to

generate synthetic data for ml

Sparisoma Viridi
2 mins read ·

How to generate synthetic data for ML understanding

intro

In order to improve AI models, protect sensitive data, and mitigate bias, computer can augment or replace real data, where such kind of data known as synthetic data 1. For illustrating how to generate synthetic data, a session has been prepared 2, where it is using available working code for the analysis 3.

code

Dataset with two classes A and B is generated, with features X1, X2, X3 and output Y with following code.

import random as rnd
n = 1000
xx = []; yy = []; zz = []; label=[]

xmin = 10; xmax = 50
ymin = 40; ymax = 90
zmin = 70; zmax = 90
for i in range(n//2):
    x = rnd.random() * (xmax - xmin) + xmin
    y = rnd.random() * (ymax - ymin) + ymin
    z = rnd.random() * (zmax - zmin) + zmin
    xx.append(x)
    yy.append(y)
    zz.append(z)
    label.append('A');

xmin = 30; xmax = 80
ymin = 20; ymax = 70
zmin = 10; zmax = 30
for i in range(n//2,n):
    x = rnd.random() * (xmax - xmin) + xmin
    y = rnd.random() * (ymax - ymin) + ymin
    z = rnd.random() * (zmax - zmin) + zmin
    xx.append(x)
    yy.append(y)
    zz.append(z)
    label.append('B');

import matplotlib.pyplot as plt
plt.scatter(yy, zz)
plt.show()

# https://www.geeksforgeeks.org/writing-csv-files-in-python/ [20240421]
import csv
 
# field names
fields = ['X1', 'X2', 'X3', 'Y']
 
# data rows of csv file
rows = []
for i in range(n):
    row = [
        f'{xx[i]:.3f}',
        f'{yy[i]:.3f}',
        f'{zz[i]:.3f}',
        label[i]
    ]
    rows.append(row)

# name of csv file
filename = "x123_y.csv"
 
# writing to csv file
with open(filename, 'w', newline='') as csvfile:
    # creating a csv writer object
    csvwriter = csv.writer(csvfile)
 
    # writing the fields
    csvwriter.writerow(fields)
 
    # writing the data rows
    csvwriter.writerows(rows)

And the data can be read using

# Load dataset
url = "https://raw.githubusercontent.com/dudung/datasets/main/data/synthetic/x123_y.csv"
names = ['X1', 'X2', 'X3', 'Y']
dataset = read_csv(url, names=names, header=0)

where it has one line for header X1,X2,X3,Y. The dataset x123_y.csv can be downloaded.

analysis

The feature X3 plays important role in differing A and B classes.

notes

  1. Kim Martineau, “What is synthetic data?”, IBM, 8 Feb 2023, url https://research.ibm.com/blog/what-is-synthetic-data [20240421]. ↩︎

  2. Sparisoma Viridi, “ML synthetic data with Python”, OSF, 21 Apr 2024, url https://osf.io/wqv3z [20240421]. ↩︎

  3. Jason Browniee, “Your First Machine Learning Project in Python Step-By-Step”, Machine Learning Mastery, 26 Sep 2023, url https://machinelearningmastery.com/machine-learning-in-python-step-by-step/ [202400421]. ↩︎

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