Map Feature
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
def map_feature(x1, x2): | |
''' | |
Maps the two input features to quadratic features. | |
Returns a new feature array with more features, comprising of | |
X1, X2, X1 ** 2, X2 ** 2, X1*X2, X1*X2 ** 2, etc... | |
Inputs X1, X2 must be the same size | |
''' | |
x1.shape = (x1.size, 1) | |
x2.shape = (x2.size, 1) | |
degree = 6 | |
out = ones(shape=(x1[:, 0].size, 1)) | |
m, n = out.shape | |
for i in range(1, degree + 1): | |
for j in range(i + 1): | |
r = (x1 ** (i - j)) * (x2 ** j) | |
out = append(out, r, axis=1) | |
return out | |
#load the dataset | |
data = loadtxt('ex2data2.txt', delimiter=',') | |
X = data[:, 0:2] | |
y = data[:, 2] | |
pos = where(y == 1) | |
neg = where(y == 0) | |
scatter(X[pos, 0], X[pos, 1], marker='o', c='b') | |
scatter(X[neg, 0], X[neg, 1], marker='x', c='r') | |
xlabel('Microchip Test 1') | |
ylabel('Microchip Test 2') | |
legend(['y = 1', 'y = 0']) | |
#show() | |
m, n = X.shape | |
y.shape = (m, 1) | |
it = map_feature(X[:, 0], X[:, 1]) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Hi, your code serves as a perfect learning material!
I don't get the point of setting y.shape=(m,1). Isn't y already of that size?