Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

split plot_rbf_parameters.py's plot into two

- plot_rbf_parameters.py originally had two plots
  combined into one.  They have been split apart
  again.
  • Loading branch information...
commit 5fab80928fe357ca1f4cb8c59c016899340778eb 1 parent e27b310
@duckworthd duckworthd authored
Showing with 10 additions and 15 deletions.
  1. +10 −15 examples/svm/plot_rbf_parameters.py
View
25 examples/svm/plot_rbf_parameters.py
@@ -4,11 +4,7 @@
==================
This example illustrates the effect of the parameters `gamma`
-and `C` of the rbf kernel SVM. It draws two plots, the first being
-a heatmap of accuracy during cross validation over parameters
-enumerated by grid search, and the latter being a visualization of
-the decision function as a function of the feature vector in 2D
-for a variety of parameter settings.
+and `C` of the rbf kernel SVM.
Intuitively, the `gamma` parameter defines how far the influence
of a single training example reaches, with low values meaning 'far'
@@ -17,10 +13,14 @@
against simplicity of the decision surface. A low C makes
the decision surface smooth, while a high C aims at classifying
all training examples correctly.
+
+Two plots are generated. The first is a visualization of the
+decision function for a variety of parameter values, and the second
+is a heatmap of the classifier's cross-validation accuracy as
+a function of `C` and `gamma`.
'''
print __doc__
-import matplotlib.gridspec as gridspec
import numpy as np
import pylab as pl
@@ -85,19 +85,15 @@
# visualization
#
# draw visualization of parameter effects
-pl.figure(0, figsize=(16, 6))
+pl.figure(0, figsize=(8, 6))
xx, yy = np.meshgrid(np.linspace(-5, 5, 200), np.linspace(-5, 5, 200))
-gs2 = gridspec.GridSpec(3, 3)
-gs2.update(left=0.5, right=0.95, bottom=0.05, top=0.95)
for (k, (C, gamma, clf)) in enumerate(classifiers):
# evaluate decision function in a grid
Z = clf.decision_function(np.c_[xx.ravel(), yy.ravel()])
Z = Z.reshape(xx.shape)
# visualize decision function for these parameters
- row = k / 3
- col = k % 3
- pl.subplot(gs2[row, col])
+ pl.subplot(len(C_2d_range), len(gamma_2d_range), k + 1)
pl.title("gamma {}, C {}".format(gamma, C), size='medium')
# visualize parameter's effect on decision function
@@ -116,9 +112,8 @@
scores = np.array(scores).reshape(len(C_range), len(gamma_range))
# draw heatmap of accuracy as a function of gamma and C
-gs = gridspec.GridSpec(1, 1)
-gs.update(left=0.05, right=0.45, bottom=0.15, top=0.95)
-pl.subplot(gs[0, 0])
+pl.figure(1, figsize=(8, 6))
+pl.subplots_adjust(left=0.05, right=0.95, bottom=0.15, top=0.95)
pl.imshow(scores, interpolation='nearest', cmap=pl.cm.spectral)
pl.xlabel('gamma')
pl.ylabel('C')
Please sign in to comment.
Something went wrong with that request. Please try again.