Dear experts,

I’m experiencing a dramatic improvement in cross-validation when data are 
standardised 

I mean accuracy increased from 48% to 100% when I shift from X to X_scaled = 
preprocessing.scale(X)

Does it make sense in your opinion?

Thank You a lot for any suggestion,

Fabrizio



my CODE:

import numpy as np
from sklearn import preprocessing
from sklearn.svm import LinearSVC
from sklearn.cross_validation import StratifiedShuffleSplit

# 14 features, 16 samples dataset
data = loadtxt(“data.txt")
y=data[:,0]
X=data[:,1:15]
X_scaled = preprocessing.scale(X)

sss = StratifiedShuffleSplit(y, 10000, test_size=0.25, random_state=0)
clf = svm.LinearSVC(penalty="l1", dual=False, C=1, random_state=1)
cv_scores=[]

for train_index, test_index in sss:
   X_train, X_test = X_scaled[train_index], X_scaled[test_index]
   y_train, y_test = y[train_index], y[test_index]
   clf.fit(X_train, y_train)
   y_pred = clf.predict(X_test)
   cv_scores.append(np.sum(y_pred == y_test) / float(np.size(y_test)))

print "Accuracy ", np.ceil(100*np.mean(cv_scores)), "+/-", 
np.ceil(200*np.std(cv_scores))



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