Drawing Andrews Curves Using Pandas

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Overview:

  • Andrews curves project multivariate data, through the vector formed by the co-efficients of the finite Fourier series on to a two-dimensional space.
  • The Fourier series and the vector is given by
  1. x(t) = x1/√2 +x2sin(t) +x3cos(t) +x4sin(2t) +x5cos(2t)
  2. 1/√2,sin(t),cos(t),sin(2t),cos(2t), . .
  • Each data point "t" in the multivariate data, is represented by a curve between −π and π.
  • If two curves appear closer in the Andrews Curves plot, then these two data points are indeed closer.
  • Given a "class" column of a pandas DataFrame, the function andrews_curves() from the plotting module of the pandas library, draws Andrews curves.

Example 1:

# Example Python program that plots
# Andrews curves for a multivariate data
# Data Courtesy: https://archive.ics.uci.edu/ml/datasets/Breast+Tissue

import pandas as pds
import matplotlib.pyplot as plt

# Read data from a CSV file into a DataFrame
df = pds.read_csv("BreastTissue.csv");

# Draw Andrews curves
pds.plotting.andrews_curves(df, "Class");

plt.title("Breast tissue classification using Andrews Curves:");
plt.show(block=True);

Output:

Drawing Andrews Curves using Pandas plotting module

lag plot

parallel coordinates

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