CODEWITHSUNDEEP
pythonpython-3.xmachine-learningscikit-learn
Somesh Gupta
Somesh Gupta

Reputation: 321

what does the X[y==0,1] operation do here in the code?

In this code: 

from sklearn.datasets import make_moons
import matplotlib.pyplot as plt

X, y = make_moons(n_samples=100, random_state=123)
plt.scatter(X[y==0,0], X[y==0,1], color='red', marker='^', alpha=0.5)
plt.scatter(X[y==1,0], X[y==1,1], color='blue', marker='o', alpha=0.5)
plt.show()

What exactly does the operation X[y==0,0] do to the dataset X?

Upvotes: 1

Views: 3731

Answers (2)

shikha kansal
shikha kansal

Reputation: 1

(X[y==0,0], X[y==0,1]) explaination:

X[y==0,0]

'y==0', This puts a condition that wherever y is 0. i.e only take those instances where y is 0

',0' , This is element of X at index 0 in a list or X[0]

X[y==0,0], This whole expression is the x co-ordinate and it says, 'Only in those lists where y is 0(ignore rest of the lists), take X[0] as x-coodinate.

X[y==0,1], This whole expression is the y co-ordinate and it says, 'Only in those lists where y is 0(ignore rest of the lists), take X[1] as y-coodinate.

(X[y==0,0], X[y==0,1]), This whole expression is the x and y cordinates of a point in the scatterplot

Upvotes: -1

not link
not link

Reputation: 870

In this case, both the variables X and y are of type numpy.ndarray.

And looking at the variables we can see that the variable X has shape (100, 2). This means that X has 100 rows and 2 columns. Similarly, y has shape (100,) and is thus just a 1-D vector. It happens to hold only 0s and 1s.

Thus X[y==0,0] finds all the rows of X that have a y value of 0 (y == 0), and are in the first column of X

Upvotes: 4

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