TheilSen Regressor: Effect of parameters

TheilSen Regressor-Effect of parameters on output 

TheilSenRegressor technique is tested here to see their accuracy in terms of output.

Python program:

>>> import numpy as np

>>> import matplotlib.pyplot as plt

>>> from matplotlib.colors import ListedColormap

>>> from sklearn import neighbors, datasets

>>> n_neighbors = 24

>>> iris = datasets.load_iris()

>>> x = iris.data[:, :2]

>>> y = iris.target

>>> h = .02

>>> cmap_bold = ListedColormap(['firebrick', 'lime', 'blue'])

>>> cmap_light = ListedColormap(['pink', 'lightgreen', 'paleturquoise'])

//Plotting the analysis//

>>> from sklearn import linear_model
>>> clf = linear_model.TheilSenRegressor()
>>> clf.fit(x, y)

TheilSenRegressor(copy_X=True, fit_intercept=True, max_iter=300,
         max_subpopulation=10000, n_jobs=1, n_subsamples=None,
         random_state=None, tol=0.001, verbose=False)

a) Effect of maximum iterations (max_iter):

>>> for max_iter in [1, 2, 5, 50, 100, 250]:
...     clf = linear_model.TheilSenRegressor(max_iter=max_iter)
...     clf.fit(x, y)
...     x_min, x_max = x[:, 0].min() -1, x[:, 0].max() +1
...     y_min, y_max = x[:, 1].min() -1, x[:, 1].max() +1
...     xx, yy = np.meshgrid(np.arange(x_min, x_max, h), np.arange(y_min, y_max, h))
...     z = z.reshape(xx.shape)
...     plt.figure()
...     plt.pcolormesh(xx, yy, z, cmap=cmap_light)
...     plt.scatter(x[:, 0], x[:, 1], c=y, cmap=cmap_bold, edgecolor='k', s=24)
...     plt.xlim(xx.min(), xx.max())
...     plt.ylim(yy.min(), yy.max())
...     plt.title("TheilSenRegressor (max_iter='%s')" %(max_iter))
...

b) Effect of number of jobs (n_jobs):

>>> for n_jobs in [1, 2, 5, 50, 100, 250]:
...     clf = linear_model.TheilSenRegressor(n_jobs=n_jobs)
...     clf.fit(x, y)
...     x_min, x_max = x[:, 0].min() -1, x[:, 0].max() +1
...     y_min, y_max = x[:, 1].min() -1, x[:, 1].max() +1
...     xx, yy = np.meshgrid(np.arange(x_min, x_max, h), np.arange(y_min, y_max, h))
...     z = z.reshape(xx.shape)
...     plt.figure()
...     plt.pcolormesh(xx, yy, z, cmap=cmap_light)
...     plt.scatter(x[:, 0], x[:, 1], c=y, cmap=cmap_bold, edgecolor='k', s=24)
...     plt.xlim(xx.min(), xx.max())
...     plt.ylim(yy.min(), yy.max())
...     plt.title("TheilSenRegressor (n_jobs='%s')" %(n_jobs))
...