python how to plot classification data

Question

I'm unable to plot the data for classification algo using numpy as it throws this error ValueError: x and y must be the same size

My data in the data variable look like this:

[[ 34.62365962  78.02469282   0.        ]
 [ 30.28671077  43.89499752   0.        ]
 [ 35.84740877  72.90219803   0.        ]
 [ 60.18259939  86.3085521    1.        ]
 [ 79.03273605  75.34437644   1.        ]
 [ 45.08327748  56.31637178   0.        ]
 [ 61.10666454  96.51142588   1.        ]
 [ 75.02474557  46.55401354   1.        ]]

Code:

data=np.loadtxt('ex2data1.txt',delimiter=',',dtype=None)
X = data[:, [0,1]]
y = data[:, 2]
pylab.scatter(X,y)
pylab.show()

I'm trying to plot this:

Answer 1

# Visualising the Training set results
from matplotlib.colors import ListedColormap
X_set, y_set = X_train, y_train
X1, X2 = np.meshgrid(np.arange(start = X_set[:, 0].min() - 1, stop = X_set[:, 0].max() + 1, step = 0.01),
                     np.arange(start = X_set[:, 1].min() - 1, stop = X_set[:, 1].max() + 1, step = 0.01))
plt.contourf(X1, X2, cla.predict(np.array([X1.ravel(), X2.ravel()]).T).reshape(X1.shape),
             alpha = 0.75, cmap = ListedColormap(('red', 'green')))
plt.xlim(X1.min(), X1.max())
plt.ylim(X2.min(), X2.max())
for i, j in enumerate(np.unique(y_set)):
    plt.scatter(X_set[y_set == j, 0], X_set[y_set == j, 1],
                c = ListedColormap(('red', 'green'))(i), label = j)
plt.title('KNN (Training set)')
plt.fig(figsize=(12,6))
plt.xlabel('Age')
plt.ylabel('Estimated Salary')
plt.legend()
plt.show()

See the example